Rinse and drain the lentils, looking over them carefully for any small stones.
Place the lentils in a pot with the water over medium heat, bring them to a simmer and then reduce heat to low. Cook covered with a lid checking them often to avoid over-cooking.
Meanwhile, whisk together the olive oil, lemon juice, salt and pepper. Taste and adjust as needed.
When the lentils are tender (but not mushy), drain and toss with the dressing and remaining ingredients.
Chill salad for at least 30 minutes before serving.