We switched to these over flank and skirt about 5 years ago. I only buy them from Blue Max butchers on Canyon road in Puyallup.
I marinate for 6 hours in a soy sauce base with orange, lime, lemon juice, coriander seed, cumin, jalapeño peppers, cayenne pepper, garlic powder, diced onions, then grill over hot charcoal till medium rare. Dice up small for tacos. Add avacado and corn salsa. Mic drop.