Rinse the beans. Finely chop the onion. Peel the carrots and celery and cut into small cubes. Cut the tomato into medium cubes. Wash the parsley and do not cut too finely. Dissolve tomato paste, salt, pepper, sugar and lemon splash in water.
Put everything in a baking dish with the olive oil and stir well. The contents should not necessarily be under water, but the liquid should already visibly settle, so do not choose a casserole dish that is too large. If necessary, use a little more water and tomato paste.
Bake in the oven at around 150-160 degrees for about 2-3 hours. You should stir vigorously once every half hour and the liquid should be largely boiled off at the end.
Leave the mold in the switched-off oven for about a quarter of an hour and then let it cool down to room temperature.
I know the beans for grilling in this cold state, with bread and tzatziki a dream!