Slow-Roasted Cajun-Spiced Prime Rib
A tender, juicy prime rib roast seasoned with a bold Cajun spice blend and slow-roasted to medium rare perfection. This american-inspired beef ready in about 200 minutes pairs prime rib roast (bone-in), olive oil, paprika for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 650 calories and feeds 8, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.
Ingredients
- 5 lbs prime rib roast (bone-in)
- 2 tbsp olive oil
- 2 tbsp paprika
- 1 tsp cayenne pepper
- 1 tbsp garlic powder
- 1 tbsp onion powder
- 1 tsp dried thyme
- 2 tsp salt
- 1 tsp black pepper
Equipment for this recipe
Top-rated tools to make this recipe successfully.
Instructions
- Step 1: Preheat your oven to 250°F (120°C). In a small bowl, combine 2 tbsp paprika, 1 tsp cayenne pepper, 1 tbsp garlic powder, 1 tbsp onion powder, 1 tsp dried thyme, 2 tsp salt, and 1 tsp black pepper to create the Cajun spice rub.
- Step 2: Pat dry the 5 lbs prime rib roast with paper towels. Rub 2 tbsp olive oil evenly over the roast, then massage the Cajun spice rub all over the surface, ensuring full coverage.
- Step 3: Place the seasoned prime rib on a wire rack set inside a roasting pan. Insert a meat thermometer into the thickest part of the roast.
- Step 4: Roast in the preheated oven for approximately 3 hours, or until the internal temperature reaches 130°F (54°C) for medium rare.
- Step 5: Remove the roast from the oven and tent loosely with foil. Allow it to rest for 20 minutes, during which the temperature will rise slightly to reach perfect medium rare doneness and the juices will redistribute.
- Step 6: Slice the prime rib against the grain into 1/2-inch thick slices and serve with your preferred sides.
Frequently asked questions
How long does Slow-Roasted Cajun-Spiced Prime Rib take to make?
Total time is about 200 minutes (20 min prep + 180 min cook). Most home cooks find this fits comfortably into a weeknight; double the batch on Sunday for two dinners.
How do I store leftover Slow-Roasted Cajun-Spiced Prime Rib?
Cool to room temperature within 2 hours, then store in an airtight container in the fridge for up to 4 days. Reheat covered in a 350°F oven for 10-12 minutes, or microwave at 70% power in 60-second bursts to keep prime rib roast (bone-in) from drying out.
Can I substitute ingredients in Slow-Roasted Cajun-Spiced Prime Rib?
Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.
How do I scale Slow-Roasted Cajun-Spiced Prime Rib for a different number of people?
The recipe is written for 8 servings. Multiply each ingredient by (your serving target / 8). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.
What goes well with Slow-Roasted Cajun-Spiced Prime Rib?
American beef like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.
