Prep the zucchini: Preheat your oven to 400°F (200°C). Slice each zucchini in half lengthwise.
Use a spoon to scoop out the center seeds, leaving a 1/4-inch border so the “boat” holds its shape. Lightly brush the cut sides with olive oil and sprinkle with a pinch of salt.
Par-bake the boats: Arrange the zucchini halves cut-side up on a baking sheet. Bake for 10 minutes to soften slightly.
This step helps them finish cooking evenly once filled.
Cook the filling: While the zucchini bakes, heat a large skillet over medium heat with the remaining olive oil if needed. Add the onion and cook 3–4 minutes until softened. Stir in the garlic and cook 30 seconds until fragrant.
Brown the meat: Add the ground beef or turkey.
Break it up with a spoon and cook until browned and no longer pink, about 5–7 minutes. Drain excess fat if needed.
Season it right: Stir in chili powder, cumin, paprika, oregano, salt, pepper, and red pepper flakes if using. Cook 1 minute to bloom the spices.
Make it saucy: Add tomato sauce and tomato paste.
Simmer 2–3 minutes until thickened and well combined. Taste and adjust salt. Remove from heat, then stir in half the cilantro and a squeeze of lime.
Fill and top: Spoon the taco filling into each par-baked zucchini boat, packing it in.
Sprinkle evenly with shredded cheese.
Bake to finish: Return the tray to the oven for 8–10 minutes, until the zucchini is tender and the cheese is melted and bubbly.
Garnish and serve: Top with the remaining cilantro and any extras you like—avocado, jalapeños, salsa, or a dollop of sour cream or Greek yogurt. Serve hot with lime wedges.