Adapted from allrecipes.com and www.health-bent.com.
2 pounds beef tenderloin tips
16 ounces mushrooms - I used baby bella and shiitake, sliced
1 acorn squash, halved lengthwise, seeded, and then cut crosswise into 1/2-inch slices (to make crescent shapes)
freshly ground black pepper
1/4 cup + 1 Tbsp extra virgin olive oil
1/2 cup balsamic vinegar, divided
1 Tbsp grainy Dijon mustard
2 tsp minced fresh rosemary
2 Tbsp grass-fed butter, divided
4 small onions, cut into 1/2-inch dice (about 2 cups)
- Preheat oven to 400 degrees F.
- Season tenderloin with salt and pepper.
- Combine oil, vinegar, mustard, and rosemary in a medium bowl. Place tenderloin in balsamic mixture and let marinade for 30 minutes.
- Place acorn squash on a parchment-lined rimmed baking sheet. Drizzle with 1 Tbsp olive oil and season with salt and pepper. Bake for 15 minutes or until tender but not mushy. Keep warm.
- While meat marinates, warm butter in a large skillet over medium heat. Add onions and saute for 15-20 minutes, stirring occasionally, until they begin to caramelize.
- Add mushrooms and continue to cook for 5-10 minutes or until mushrooms are cooked. At the same time in another large skillet, warm the remaining 1 Tbsp butter. Add meat to the pan and transfer the marinade to a small sauce pan. Simmer the marinade for 2 minutes to kill any bacteria.
- Saute steak for 3-4 minutes or until medium rare. Add it to the mushroom mixture and stir to combine.
- To serve, divide steak and mushroom mixture evenly among plates. Place acorn squash on the side and drizzle with balsamic marinade.