While the steaks are marinating, in a large sauce pan over medium heat, warm 2 tablespoons olive oil. Add the tomatillos and saute for 3-5 minutes, or until tender, then remove from heat.
Place all ingredients into a food processor and pulse until finely chopped.
Pour into a bowl and chill in refrigerator for 30 minutes.
Drain excess liquid, season to taste with salt and freshly ground pepper, then serve.