Place a large nonstick skillet over medium-high heat. Add the onion, garlic and ground turkey into the skillet. Season with salt and pepper. Cook for 8 to 10 minutes, breaking apart with a wooden spoon or spatula while it cooks. Add black beans, chili powder, cumin and salsa. Cook 2-3 minutes additional minutes.
Meanwhile, as the turkey cooks cut the zucchini in half, lengthwise. Use a spoon to scoop the seeds and center out of each zucchini half, leaving about ¼ inch thick zucchini boat.
Place the zucchini (cut-side up) in a 9X13 baking dish. Spoon the turkey mixture into the six zucchini boats.
Cover the baking dish with foil. Bake for 20-30 minutes or until zucchini boats are heated throughout and zucchini is cooked a bit, but not too soft/limp.
Remove foil and serve boats with tomatoes, avocado and jalapeño slices. Serve with chips and salsa if desired.
Notes
If you decide to use cheese, sprinkle a little on each zucchini boat before covering the baking dish with foil and baking as directed.