Mix all the spices together in a small bowl.
Rub spice mixture onto sirloin steak.
Heat oil in a large skillet.
Sear steak on both sides, about 3-5 minutes per side. Do not overcook.
Remove steak from pan and allow steak to rest for 5 minutes.
Slice steak into thin strips and then dice into ½ inch chunks.
Place a tortilla onto work surface and spread out about ½ cup of cheese.
Top with diced tomatoes, diced avocado, minced Jalapeno, black beans and corn.
Place diced steak on top of the fillings on each tortilla.
Sprinkle with a generous layer of cheese.
Melt a tablespoon of butter in a heavy bottom skillet over medium heat.
Place quesadilla in the skillet and cook until browned. Flip over and cook until the other side is browned and the cheese is melted.
Repeat. Assemble and cook remaining quesadillas.
Cut each cooked quesadilla into wedges.
Serve with lime wedges and top with a generous dollop of sour cream and chopped cilantro.