Prepare the tomatoes:
Slice the tops off the tomatoes and scoop out the insides using a spoon (reserve for another use or discard). Lightly salt the inside and turn upside down on paper towels to drain while you make the filling.

Cook the filling:
In a skillet over medium heat, sauté onions for 2 minutes until soft. Add garlic and cook another 30 seconds. Add ground beef and cook until browned, breaking it up as it cooks. Stir in taco seasoning, a splash of water, and cook for another 2–3 minutes. Mix in corn and black beans if using.

Fill the tomatoes:
Place the hollowed tomatoes upright in a baking dish. Spoon the taco filling into each one, packing it in. Top each with a generous sprinkle of cheese.

Bake:
Preheat oven to 180°C (350°F). Bake the filled tomatoes for 10–15 minutes, or until the cheese is melted and tomatoes are slightly tender but still hold their shape.

Garnish and serve:
Top with sour cream, guacamole, and fresh coriander. Serve immediately with tortilla chips or a simple salad.

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