Put the beluga lentils in a sieve and wash. Then bring to boil with the water in a saucepan. Reduce the heat and let the lid simmer for about 30 minutes until the lentils are firm to the bite. Only at the end of the cooking time add the salt. Drain into a sieve and pour into a bowl.
Heat olive oil in a pan and fry the chopped red onion in it. Add to the lentils.
Wash the cucumber and cut into strips with a peeler together with the skin. Add 2/3 of the strips to the lentils, set aside the rest. Add 2/3 of the chopped watermelon to the lentils. Add the mint.
Mix all the ingredients for the dressing and mix in the lentil salad. Arrange the salad on plates and serve with the remaining cucumber strips and watermelon pieces.
Wellcuisine-Tipp
If you want, you can serve crumbled feta or fried Haloumi cheese with the salad.