Boneless Short Ribs with Charred Green Onion Salsa

1 1/2 pounds boneless beef short ribs, at room temperature

6 tablespoons vegetable oil, divided

2 bunches green onions, ends and green tops trimmed

1/2-pound tomatillos, husked, rinsed and halved

1 jalapeño, seeded

1/4 cup cilantro leaves

Juice of 2 limes

1/2 teaspoon ground cumin

Salt and pepper

Heat oven to 425F. Line a baking sheet with foil. Season short ribs with salt and pepper. Heat 2 tablespoons oil in a large skillet over medium high heat until smoking. Sear short ribs until browned on both sides, about 4 minutes per side. 

Transfer to prepared baking sheet and place in the oven to finish cooking until medium rare, about 10 minutes. 

Meanwhile, make salsa. Add 2 tablespoons oil to skillet, then spread green onions in a single layer and cook until charred, about 3 minutes. Turn and cook on the other side, 3 minutes more. Transfer to cutting board and chop into 1-inch pieces. 

Add tomatillos and jalapeño to pan and cook until charred, about 2 minutes. 

Transfer onions, tomatillos and jalapeño to the bowl of a food processor. Add cilantro, lime juice, cumin and 1/2 teaspoon salt. Process until chopped.

Remove short ribs from oven and let rest for 5 minutes before slicing. Serve with salsa.