My Favorite's Favorite

Alex loves these steak tacos at a Mexican restaurant down the street, and I thought I would try to replicate them.  There's nothing fancy about them, just steak, diced onions, and cilantro in a tortilla.  I used flank steak, because it's thinner it cooks quickly (requirement for a weeknight meal).  I marinated the steak for about an hour or two in lime juice, cilantro, olive oil, 2 tsp apple cider vinegar, garlic.  I cooked on a stove top cast iron grill pan for about 7-8 minutes on each side.  When I got up this morning, even the leftovers were gone... too bad because I was planning on making steak and eggs for dinner!  Back to the drawing board.

Anybody have an amazing recipe for white chili?