To make coffee rub, add brown sugar, coffee, cocoa powder, cayenne pepper and cinnamon in a bowl. Mix well to combine.
Set broiler on high. Season steak with salt and 1 tsp cumin, then generously cover with coffee rub. Broil for 6 minutes per side.
While steak is broiling, slice bell peppers and onions and place on large baking sheet. Drizzle vegetables with olive oil, then sprinkle with salt and cumin. Place baking sheet in broiler for 6 minutes (when flipping steaks).
Remove veggies and steak from broiler. Slice steak and mix with peppers and onions. Place on large serving platter and garnish with jalapeno slices and lime wedges.
Serve with your choice of flour tortillas, tortilla chips, salsa, guacamole or avocado slices.