How long to cook a 12lb prime rib

Let me show you how to roast a perfect prime rib, step by step, with proven, fool-proof method using reverse sear technique as seen on Serious Eats.

Oh my gosh, do I love me some prime rib!! Thick, juicy and melt-in-your-mouth tender, there is nothing better than perfectly cooked prime rib.

If you’d asked me “How would you like your steak?” like 10 years ago, when I just landed in the U.S., I’d tell you firmly, “Well done.” Cringe, cringe, I know!! Though we eat a lot of beef in Mongolia, steak isn’t common there. And we’re just not accustomed to pink meat. In fact, it took me good 2 years to start ordering medium done steaks. That’s when I met my rancher husband, who wouldn’t let me order well done (aka ruined) steaks.

Fast forward 8 years, I now cook medium and sometimes even medium rare steaks for myself. Oh how things change!

What’s reverse searing method?

When you have this beautifully marbled, perfectly frenched prime rib, you don’t want to mess up, especially if you’re making it for a special occasion. But don’t let the fear stop you from serving this masterpiece for a holiday meal. I’m going to show you a fool-proof, proven method to roast a perfect prime rib!

Now, listen read closely…

You’ve probably heard of searing the meat before roasting to lock in the juices, right? And no doubt, there’s place and time for that trusty technique, but when it comes to roasting a prime rib, that’s not really an ideal method. And I’m not just a crazy lady talking crazy things on the internet.

J. KENJI LÓPEZ-ALT of Serious Eats did all the testing and perfecting the art of roasting a perfect prime rib in this article.

There are 3 things he was looking for in a perfect prime rib:

1. Deep brown, crispy exterior.
2. Minimum overcooked layer between the crust and interior, aka gray zone.
3. Maximum juiciness.

He achieved all three criteria by reverse searing method. What is reverse searing, you ask?

Well, that’s when you cook the prime rib at the very low temperature until it reaches 120°F for medium rare, and then you roast it at the very high temperature for a short period of time. But here’s the important part: before searing at high temp, you’ll need to take the roast out of the oven and let it rest while oven is preheating to 500°F. This way, the roast won’t overcook, because as you know, it takes at least 20 minutes to heat an oven to that high temp, plenty of time to ruin a good roast!

Tip

For perfectly crispy crust, make sure to dry out the roast by resting it uncovered in the fridge overnight.

And while at it, go ahead and salt it too, so that it has plenty of time to penetrate the meat all the way inside.

Let me know if you try this method. I know you won’t regret it.

Thank you for reading!

Prep: 15 minutes

Cook: 4 hours

Total : 5 hours

• ▢ 5-10 lbs (or 4-rib) prime rib
• ▢ 1 tablespoon coarse kosher salt
• ▢ 2 teaspoons ground cumin
• ▢ 1 teaspoon ground black pepper
• ▢ 1 teaspoon garlic powder

Optional Add-Ins:

• ▢ A head of garlic
• ▢ Cherry tomatoes
• ▢ Asparagus

Note: I test all my recipes with both measurements for the most precise and accurate result!

Prep:

• Place an unwrapped prime rib on a tray. Generously salt all over and refrigerate overnight to air-dry the outside of the prime rib.

• Bring the prime rib to room temperature before roasting. It usually takes about 2 hours out on the counter.

• Mix the cumin, black pepper and garlic powder and evenly spread all over the meat.

• If roasting garlic, slice the top off, drizzle some olive oil and wrap in a foil.  (Here's my detailed roasted garlic recipe.)

Roast:

• Preheat the oven to 200°F (95°C).

• Place the prime rib on a roasting pan bone side down (fat side up). (Since I wrote this post, I bought this roasting pan, and highly recommend it.)

• Roast the meat in the oven until the center of the roast reads 120°F (50°C) on a meat thermometer for medium-rare, or 130°F (55°C) for medium doneness, about 3.5-4 hours. (This Thermapen Mk4 meat thermometer is my favorite! Super quick and reliable! <- affiliate link)

Rest:

• Remove the prime rib from the oven, cover with a foil and rest for about 30 minutes.

Sear:

• Increase the oven temperature to 500°F (260°C).

• 10 minutes before serving, pop the prime rib into the oven, uncovered, and cook it until it’s nice and brown, and crisp on the outside, about 6-10 minutes. If desired, roast the cherry tomatoes and asparagus together. Serve immediately.

Calories: 679kcal (34%)Carbohydrates: 1gProtein: 31g (62%)Fat: 60g (92%)Saturated Fat: 25g (156%)Polyunsaturated Fat: 2gMonounsaturated Fat: 26gCholesterol: 137mg (46%)Sodium: 800mg (35%)Potassium: 515mg (15%)Fiber: 1g (4%)Sugar: 1g (1%)Vitamin A: 6IUVitamin C: 1mg (1%)Calcium: 22mg (2%)Iron: 4mg (22%)

* Disclaimer: All nutrition information are estimates only. Read full disclosure here.

Course:Main Course

Cuisine:American

If you have have a boneless prime rib, check out this post: