Run the rusk under a spray of water (about 4 to 6 tablespoons) to moisten. Grate the tomato with a vegetable grater (or the large grate on a multi-grater) into a strainer over a bowl so most of the liquid drain off.
Spread the grated tomato on the rusk and top with cheese. Sprinkle with pepper and a good amount of oregano, and drizzle with olive oil.
1/2 of a large round barley rusk (about 5 inches diameter)
1 large tomato (or 2 small ripe tomatoes, coarsely grated, discard skin)
2 to 3 heaping tablespoons of feta cheese (or aged myzithra, crumbled or grated)
2 to 3 teaspoons olive oil (extra virgin)
Black pepper to taste
Pinch oregano (Greek rigani)