Southwest Beef Lettuce Wraps

• 1 tablespoon olive oil
• 1 red bell pepper, diced
• 1 jalapeno, diced
• 1/2 yellow onion, diced 
• 2 pounds ground beef 
• 1/2 teaspoon chili powder 
• 1/2 teaspoon ground cumin 
• 1/2 teaspoon kosher salt 
• 1/2 teaspoon ground black pepper 
• 1/4 teaspoon crushed red pepper 
• 8 medium inner romaine lettuce leaves (from a romaine heart) 

Toppings:

• 1 cup shredded pepper jack cheese
• 1/2 cup chopped tomatoes 
• 2 red onions, diced 
• 2 avocados, each sliced into 8 slices
• 2 ears fresh corn, cooked and kernels sliced off 
• 1 container sour cream 
• 1/2 cup fresh cilantro leaves
• 2 limes, each cut into 4 wedges