Drain and rinse the lentils. Place them in a medium saucepan along with 2cups water. Bring the water to a boil; lower the heat and simmer until the lentils are tender, about 15~18 minutes.
Drain any extra water from the lentils and place them in a mixing bowl.
Steam the broccoli until tender and add to the lentils. Season with salt and pepper. Stir in the thinly sliced red onion. Mix well.