COOK lentils in a litter of water with a garlic clove, bay, onion and salt. When they get cooked, drain and let it cool. Settle, roast peppers, take out the seeds and slice them, also slice the onion.
MIX in a bowl lentils, peppers and red onion.
PREPARE vinaigrette mixing until vinegar emulsifies, the mayonnaise, mustard, oil, sugar and salt.
DRESS your salad at the moment.