Remove the tops of the tomatoes and slightly trim the bottom for stability. Scoop out the insides with a spoon and roughly chop the removed parts.

Finely chop the onion and microwave it in a heatproof container for 1 minute at 600W. Let it cool.

In a bowl, mix breadcrumbs with the chopped tomato insides to moisten. Add ground meat, onion, and the remaining seasonings. Knead until sticky.

Place the tomato shells and tops on a baking sheet lined with parchment paper. Stuff each tomato with 1/4 of the meat mixture. Bake at 200°C for 15 minutes.