In a medium saucepan, cover lentils with water by 1 inch. Bring to a boil; reduce to a simmer. Cover, and cook until lentils are tender but still holding their shape, 15 to 20 minutes. Drain well.
Meanwhile, bring 1 cup water to a boil in a small saucepan. Stir in bulgur,1/2 teaspoon salt, and 1/4teaspoon pepper. Cover; remove from heat, and let stand until bulgur has absorbed liquid, 30 minutes.
Transfer bulgur to a large bowl. Gently stir in lentils, tomatoes, scallions, lemon juice, and oil. Serve sprinkled with feta.