Simmer the Lentils: In a medium saucepan, combine the rinsed lentils, 4 cups of water, the bay leaf, and the whole garlic clove. Bring to a boil over high heat, then immediately reduce the heat to a gentle simmer. Cover and cook for 20-25 minutes, or until the lentils are tender but still retain a firm bite.
Prepare the Vinaigrette: While the lentils cook, combine all vinaigrette ingredients (extra virgin olive oil, lemon juice, Dijon mustard, sumac, minced garlic, pepper, and salt) in a small jar with a tight-fitting lid. Seal the jar and shake vigorously for 30 seconds until the dressing is well-combined and creamy.
Toast the Nuts: Place the raw pistachios in a small, dry skillet over medium heat. Toast for 3-5 minutes, tossing frequently, until they become fragrant and lightly golden. Immediately transfer them to a small bowl to prevent burning and allow them to cool. Once cooled, give them a rough chop.
The Warm Toss: Once the lentils are cooked, drain them thoroughly in a fine-mesh sieve, discarding the bay leaf and whole garlic clove. Transfer the hot, drained lentils to a large mixing bowl. Immediately pour half of the prepared vinaigrette over the warm lentils and toss gently to coat. Let them sit for 5-10 minutes to absorb the flavors.
Final Assembly: To the bowl with the dressed lentils, add the diced cucumber, red bell pepper, red onion, chopped pistachios, and diced apricots. Add the fresh parsley and mint. Pour the remaining vinaigrette over the salad and toss everything together until every ingredient is coated. For the best flavor, allow the salad to rest for at least 15 minutes before serving.