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Why put rock salt under prime rib?

Prime rib is a delicious and impressive entrée for special occasions like holidays and celebrations. It’s a large, tender cut of beef that is seasoned, roasted, and served with au jus. Many recipes call for placing a bed of rock salt under the slab of prime rib before roasting. This technique serves an important purpose and results in a perfect roast every time.

What is the purpose of the rock salt?

There are a few key reasons why recipes suggest placing prime rib on a bed of rock salt while roasting:

  • Creates a barrier between the meat and the pan – The coarse rock salt prevents the prime rib from coming into direct contact with the metal roasting pan. This helps prevent the meat from steaming and becoming soggy on the underside.
  • Encourages moisture drainage – As the meat cooks, juices and fat will drip down into the salt. The salt helps draw out excess moisture from the meat, resulting in a nicely browned exterior.
  • Provides insulation – The bed of salt creates a layer of insulation under the meat. This allows the roast to cook slowly and evenly, preventing the bottom from overcooking.
  • Enhances flavor – As the salt draws out juices, it dissolves slightly and infuses the meat with seasoning. The salt also forms a tasty crust on the exterior of the roast.

Overall, the salt creates the ideal environment for roasting prime rib to perfection. It regulates moisture and temperature while imparting flavor in the process.

How much rock salt do you need?

A good rule of thumb is to use about 1/2 – 1 cup of rock salt per pound of prime rib being roasted. So for a 4-5 pound roast, you’ll want 2-4 cups of rock salt. It’s better to use too much than not enough, as you want to completely cover the bottom of the pan.

Look for coarse rock salt or kosher salt rather than table salt. The larger grains are more effective at absorbing moisture and providing insulation. Sea salt also works well. Just avoid salts with large crystals like Himalayan pink salt, as the sharp edges could puncture the meat.

How to prepare the rock salt bed

Preparing the rock salt bed is simple:

  1. Pat prime rib dry, and season well with spices and herbs as desired.
  2. Preheat oven to around 250-275°F. Place rock salt in the bottom of a roasting pan, spreading into an even layer. Use enough to completely cover the pan bottom in a 1/2-1 inch layer.
  3. Place seasoned prime rib directly on top of the salt, fat side up. Do not use a roasting rack.
  4. Roast for several hours until done, basting periodically. Remove from oven and tent with foil before carving.

As the meat roasts, the rock salt will draw out juices and gradually dissolve. Discard the remaining moisture and salt after cooking. Then clean and dry the roasting pan well after each use to prevent corrosion over time.

Can you reuse rock salt for prime rib?

It’s best to use fresh rock salt each time you roast prime rib. Reusing the salt increases the risk of bacterial contamination from meat juices. The old salt will also be damp and won’t provide the same insulation and absorption benefits.

However, you can reuse rock salt from prime rib to deice sidewalks and driveways! Just allow the salt to fully dry out first before storing and using on pavement.

What to do if you don’t have rock salt

While rock salt is ideal, you can still roast delicious prime rib without it in a pinch. Here are a couple substitutions:

  • Sand – Clean sand makes a good alternative insulation layer. Use a 2-3 inch deep layer in the bottom of the pan.
  • Salt alternative – Mix together 1 cup baking soda and 1 cup kosher salt. Spread this in the roasting pan instead.
  • Raise the meat – Elevate the roast using vegetables or a rack to allow air circulation underneath.

Keep in mind moisture drainage may be reduced without the rock salt, so baste the roast more frequently. Monitor oven temperature and cook times closely as well. Although not ideal, prime rib can still turn out very tasty using one of these rock salt substitutions.

Can you cook prime rib without any salt at all?

It’s possible to roast prime rib without using any type of salt or raising the meat. However, the results may not be as ideal.

Without a salt layer or rack, the bottom of the roast is more likely to overcook from direct contact with the hot metal pan. Moisture can get trapped against the pan rather than properly draining away as well.

You’ll need to carefully monitor the cooking process if forgoing the salt. Try lower heat around 225°F and frequently baste and rotate the meat. Watch for doneness early to avoid overcooking. Letting the roast rest longer before carving also allows moisture to redistribute.

While it’s not impossible to have tasty prime rib without rock salt, the salt really helps ensure the best results. Most chefs and recipes strongly recommend using an ample amount of coarse salt for the ideal flavor, moisture control, andtextures.

How the salt crust gets so hard

As the prime rib roasts, the rock salt absorbs moisture from the meat and begins to dissolve. The dissolved salt mixes with the meat juices, forming a sticky brine. This brine gradually crystalizes on the surface of the roast, creating a beautifully caramelized and flavorful crust.

The salt crust that forms helps:

  • Enhance browning through the Maillard reaction
  • Lock in moisture so the meat stays juicy
  • Boost seasoning on the exterior with a salty, savory flavor
  • Provide textural contrast between the tender interior and crispy crust

When sliced, you get gorgeous rosy slices of prime rib with a delightful crunch on the outside. The salty hard crust is part of what makes roasted prime rib so spectacular.

Can you eat the salt crust?

The tasty salt crust that forms on prime rib during roasting is completely edible. Not only is it safe to eat, it’s one of the best parts!

The crust should be well-browned and crisp from the extended roasting time. As you carve and serve the roast, make sure a bit of this coveted crust ends up on each plate.

The richly flavored and textured crust is ideal with the fork-tender meat. The saltiness provides the perfect contrast to the big beefy flavor of prime rib as well. Just be sure to trim off any unappetizing gray meat before carving and serving.

Nutrition of the salt crust

Since the salt crust is simply rock salt that has absorbed meat juices, it has minimal nutritional value itself:

Nutrient Amount
Calories Minimal (~5 per 1 tsp)
Fat None
Protein Trace
Carbs None
Sodium High (500+ mg per 1 tsp)

As you can see, the salt crust is almost entirely just sodium and minerals. But keep in mind a little goes a long way flavor-wise, so you likely won’t be eating large quantities. Enjoy the texture and seasoning it provides without worrying about high sodium consumption.

Should you wrap prime rib in foil while cooking?

Most chefs do not recommend wrapping prime rib in foil while roasting it. Instead, the roast should be uncovered in the oven to promote proper air circulation and browning.

Wrapping prime rib in foil traps steam around the meat, leading to a mushy texture and less flavor development. It can also cause the crust to become soggy and pale.

However, lightly tenting foil over just the bones or uneven ends during cooking can prevent them from over-browning. You can also tent the entire roast very loosely with foil after removing it from the oven to help retain heat while it rests.

If you want to speed up cooking, rather than using foil try increasing the oven temperature by 25°F. This will accelerate roasting without compromising texture and color.

Should you sear prime rib before roasting?

Searing prime rib before putting it in the oven is an optional step. It can help enhance flavor and color, but is not required.

To sear, first pat the roast dry and season it generously. Heat a cast iron skillet until very hot. Add just enough oil to coat the pan and carefully brown all sides of the prime rib, about 1 minute per side.

This quick sear locks in moisture and gives the meat a rich, brown crust. The meat’s surface will undergo the Maillard reaction, resulting in enhanced savory flavor.

Then transfer the seared prime rib to a roasting pan lined with rock salt and finish cooking in the oven.

Keep in mind searing may cause some splattering, so be cautious. And resist the urge to sear for too long or the interior of the roast could overcook. A quick sear just before low and slow roasting is ideal.

What herbs and spices go well with prime rib?

Part of what makes prime rib so special is how beautifully it showcases simple seasonings. Here are some classic herb and spice combinations that pair perfectly with prime rib:

  • Salt, pepper, garlic – This simple trio is all you need for incredible flavor. Use coarse salt or a rub for the crust. Generously season with pepper before searing. Add minced garlic and pepper before roasting.
  • Rosemary, thyme, garlic – These aromatic herbs infuse a wonderful woodsy flavor. Use dried herbs in the salt crust or rub. Add fresh herbs on top partway through roasting.
  • Onion and pepper – Sauteed onion and bold black peppercorns blended into a paste coat the meat with savory sweetness and heat.
  • Coffee and chili powder – Wake up the beefy taste with a coffee rub. Chili powder adds mild heat and smokiness.
  • Horseradish and mustard – Horseradish zing and mustard pungency cut through the rich meat. Mix into a spicy paste and spread on before roasting.

You really can’t go wrong pairing prime rib with simple, complementary seasonings. The high-quality meat shines when treated to just a touch of herbs, garlic, pepper, and other spices.


Placing prime rib on a bed of rock salt while roasting is a simple trick that yields incredibly moist, tender, and flavorful results every time. The salt absorbs excess moisture, insulates the meat, and imparts seasoning while creating a delicious crust.

Be sure to use a generous amount of coarse kosher or rock salt in the pan – about 1/2 to 1 cup per pound of meat. Pat the roast dry, season it well, and place directly on the salt without a rack. Roast in a low oven for several hours until perfectly medium-rare.

The savory salt crust that forms will offer the ideal contrast to the fork-tender roast. Slice and serve the prime rib so each portion includes some of the prized crust for a little crunch and salty bite. Enjoy this impressive centerpiece with family and friends on your next special occasion.