Thoroughly wash the dandelion roots and boil them with sugar for 10 – 15 minutes, depending on their size, until soft.
Drain the roots and let cool briefly.
Beat the egg, whisk it and put it on plates as well as the breadcrumbs. Pull the roots through the egg and turn them in the breadcrumbs.
Heat the oil in a frying pan and fry the dandelion roots until crispy. Drain on paper towels and add salt to taste.
Preheat the oven to 200 °C (top/bottom heat).
Wash the tomatoes, cut them in half and remove the seeds.
Place the halves in a baking dish, drizzle with a teaspoon of olive oil and bake for 30 minutes.
Peel and finely dice the onion and garlic and sauté in a teaspoon of olive oil until golden brown. Add sugar and vinegar and stir until sugar dissolves.
Pour everything into a tall cup with the remaining olive oil and puree together with the watercress. Season to taste and leave to cool.