- Preheat oven to 400 degrees.
- Pat the steaks dry with paper towels and season generously with the salt and pepper. Heat the oil and butter in a large cast iron skillet over medium high heat. Cook the steaks 3 minutes per side (making sure to cook the sides). Transfer pan to the oven and cook an additional 2 minutes. Let steaks rest for 10 minutes.
- Remove the skins from the jalapeno peppers, remove seeds and membranes. Place peppers in the bowl of the food processor with the oil, pepper, cilantro shallot, water and lime juice; process until smooth.
- Place the mango, avocado, shallots, cilantro and mesclun greens in a large bowl. Add the dressing to the bowl and toss to coat.
- Carve the steak into 1/2 inch thick slices. Mound the salad onto 4 serving plates. Fan the steak slices around the salad. Top with crumbled Cotija cheese.