Pan-Seared Beef Tenderloin with Caramelized Onions and Thyme

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

A restaurant-quality beef tenderloin seared to a perfect medium-rare, topped with deeply caramelized onions and fresh thyme for a rich, keto-friendly dinner. This American-inspired beef recipe (keto), ready in about 40 minutes, pairs beef tenderloin, onion, thyme for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 580 calories and feeds 2, so it slots cleanly into a low-carb week and pairs well with cauliflower rice or roasted green vegetables. 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.

Prep: 15 min Cook: 25 min Serves 2 American cuisine 580 cal/serving
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Ingredients

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Instructions

  1. Step 1: Season the beef tenderloin medallions with 1/2 tsp salt and 1/4 tsp black pepper on both sides.
  2. Step 2: Heat 1 tbsp avocado oil in a large skillet over medium-high heat until shimmering. Add the beef and cook for 3-4 minutes per side until a golden crust forms, then transfer to a plate and tent with foil.
  3. Step 3: Add the sliced onion and minced garlic to the same skillet, stirring to coat in the oil, and cook over medium heat for 8-10 minutes until deeply caramelized and soft.
  4. Step 4: Stir in 2 tbsp fresh thyme and cook for 1 minute until fragrant. Add 1/4 cup red wine and simmer for 2 minutes until reduced by half.
  5. Step 5: Return the beef to the skillet, spooning the onion mixture over the top, and cook for 1-2 minutes to reheat.

Frequently asked questions

How long does Pan-Seared Beef Tenderloin with Caramelized Onions and Thyme take to make?

Total time is about 40 minutes (15 min prep + 25 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 Pan-Seared Beef Tenderloin with Caramelized Onions and Thyme?

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 beef tenderloin from drying out.

Can I substitute ingredients in Pan-Seared Beef Tenderloin with Caramelized Onions and Thyme?

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 Pan-Seared Beef Tenderloin with Caramelized Onions and Thyme for a different number of people?

The recipe is written for 2 servings. Multiply each ingredient by (your serving target / 2). 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.

Is Pan-Seared Beef Tenderloin with Caramelized Onions and Thyme keto?

Yes — this recipe is tagged keto based on its ingredient list. Always cross-check labels for packaged ingredients (sauces, broths, condiments) since formulations vary by brand.

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