Wash the tomatoes. Cut large tomatoes into quarters or even smaller depending on their size. Leave small vine tomatoes on the panicle. Peel onions and garlic. Cut onions into slices and garlic into slices.
Cut goat's cheese into thick slices and feta cheese into cubes. Wash basil and cut into strips.
Place the prepared ingredients in a flat cast-iron roaster or in two aluminium grill trays without holes and season with pepper. Drip oil over it. Grill on the preheated grill at indirect heat covered for 30-40 minutes. Goes well with baguette.