Cut toast into small lozenges. Peel garlic and chop very finely. Heat fat in a small pan, add bread lozenges and roast while turning. Add garlic shortly before the end.
Wash the liver thoroughly and pat dry with kitchen paper. Cut liver into pieces. Heat oil in a pan, add liver and fry for 2-3 minutes while turning. Remove liver from the pan and set aside.
Deglaze frying fat with vinegar. Add capers and season with salt, pepper and sugar. Leave the vinaigrette to cool slightly. In the meantime, wash the cherry tomatoes and cut them in half as desired. Clean the lamb's lettuce, wash thoroughly and drain well on a sieve.
Mix lamb's lettuce, tomatoes and liver. Divide into four plates, place croutons on top and sprinkle with the vinaigrette. Serve sprinkled with pepper to taste.