Combine the lemon juice, Dijon mustard and minced garlic in a mixing bowl.
Gradually, adding just a little at a time, whisk in the olive oil. Season to taste with salt and coarsely ground black pepper.
Add the hearts of palm and the artichoke hearts, and marinate at room temperature for about three hours.Toss occasionally.
Line two plates with green leaf lettuce. Using a slotted spoon, place the salad on the plates.
Garnish with tomatoes wedges, spoon some dressing over the top, and serve.
This recipe serves two.