For the lentil salad with feta, strain the lentils well from the can or strain the lentils (best soaked in water the day before) and place in a large salad bowl.
Wash the cucumber and tomatoes and cut into bite-sized cubes. Add the cut vegetables to the bowl as well.
Also very carefully rinse the lettuce and add it to the bowl. In a small bowl or coffee cup, mix well the olive oil, lemon juice, mustard, garlic, salt and pepper. (If you like salads a little sweeter, you can also add a little honey to the marinade).
Pour the finished marinade over the salad and mix everything carefully with salad servers. If necessary, season a little. Remove the feta from the package and crumble it well, preferably with clean hands.
Before serving, sprinkle the feta over the salad.