Rinse and dry the herbs. Put them in a mortar or in a food processor, add garlic, chili pepper and a bit of coarse salt. Grind everything to a smooth paste, while adding olive oil. Thinly slice the tomatoes and arrange them on a serving plate. Spread the paste evenly on the tomatoes and crumble feta cheese on top. Season with black pepper, balsamic vinegar and olive oil.