Step 1

Bring a large pot of salted water to boil, add the lentils, turn the heat to medium, and cook just until the lentils are cooked through, about 20 minutes.

Step 2

Drain the lentils, place them in a large mixing bowl, and set them aside.

Step 3

In a smaller bowl, whisk together the mustards, lemon juice, vinegar, olive oil, and a large pinch of salt.

Step 4

Add the vinaigrette to the lentils along with the onion, tomatoes, and parsley.

Step 5

Season the salad to taste with salt and more lemon or olive oil if you like.