In a skillet over medium heat, add olive oil and sliced onions. Cook, stirring occasionally, for about 15-20 minutes until onions are golden brown and caramelized. Remove from heat and let cool slightly.

In a bowl, combine mayonnaise, Dijon mustard, lemon juice, and a pinch of salt and pepper. Stir in the caramelized onions once they have cooled. Set aside.

In a large skillet, heat over medium-high heat. Season the ground beef with garlic powder, onion powder, salt, and pepper. Cook the beef for about 5-7 minutes, breaking it apart with a spatula until browned and cooked through. Drain any excess fat.

To assemble the bowls, divide the salad greens among four bowls. Top each with cooked ground beef, cherry tomatoes, cucumber, avocado, shredded cheddar cheese, and pickles. Drizzle with caramelized onion aioli.

Serve immediately and enjoy!