Step 1Place the lentils, bay leaves, garlic, 8 cups of water and three-fourths teaspoon salt in a medium pot and bring to a boil over high heat. Reduce the heat to medium-low and simmer, uncovered, until the lentils are tender, about 20 to 25 minutes. Drain the lentils well, discarding the water, bay leaves and garlic. Transfer the hot lentils to a large bowl. Add the carrots and shallots.
Step 2In a small bowl, whisk together the oil, orange juice, vinegar, lemon juice, mustard, one-eighth teaspoon salt and a pinch of pepper, or to taste, then transfer to the bowl with the lentils and toss gently.
Step 3Add the parsley, tomatoes and mozzarella and toss again gently, just to combine, then serve.