- 2 pounds grass fed 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)
- sea salt
- 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.