Wash the lentils then put into a saucepan and cover with water by about 2 inches. Add the peeled onion, garlic and bay leaf and simmer for about 30 minutes or until the lentils are tender.
Drain and remove the onion, garlic and bay leaf. Make a vinaigrette with the olive oil, red wine vinegar, salt and pepper and mustard powder. Toss the warm lentils in the dressing.
Garnish with the hard boiled eggs cut into quarters, the olives and anchovies then sprinkle with the chopped parsley.