Preheat oven to 400 degrees F.
Trim the ends off the zucchini. Cut each zucchini in half lengthwise and scoop out the centers, leaving approximately 1/2-inch shell. Place each boat into a 9x13 inch baking dish, cut-side up.
Place a large nonstick pan over medium heat with the olive oil. Once heated, add the chopped onions and sauté 3-4 minutes, or until translucent. Add the minced garlic and cook 30 seconds, stirring.
Add the ground beef and cook until browned. Season with chili powder, onion powder, oregano, paprika, cumin, salt, and pepper. Stir to thoroughly mix.
Add salsa and diced green chiles. Stir to combine. Taste test and adjust seasonings, to taste, such as salt and pepper.
Spoon the beef mixture into each zucchini boat, pressing down to fill each one from end to end. Top with shredded cheddar cheese and a fresh squeeze of lime juice. Cover and bake for 20-25 minutes, or until the zucchini is fork-tender.
Remove and garnish with diced tomatoes, avocados, chopped cilantro, and plain greek yogurt. Or your favorite taco toppings!