8 cups water
3 teaspoons salt, divided
1 pound dried brown lentils, rinsed, drained
1/2 cup plus 2 tablespoons olive oil
1/2 cup red wine vinegar
3 tablespoons ground cumin, divided
2 tablespoons plus 2 teaspoons chili powder
2 garlic cloves, minced
1 large onion, chopped
1 1/2 pounds skinless boneless chicken breast halves, thinly sliced
1/4 teaspoon ground cinnamon
1 cup chopped fresh parsley
Combine 8 cups water and 1 teaspoon salt in heavy large saucepan over high heat. Add lentils; bring to boil. Cover, reduce heat to medium, and simmer until lentils are tender, about 20 minutes. Drain well; rinse with cold water and drain again. Place in large bowl.
Whisk 1 cup olive oil, vinegar, 2 tablespoons cumin, 2 tablespoons chili powder, garlic, and 1 teaspoon salt in large measuring cup. Pour 1 cup dressing over warm lentils and toss. Cool.
Heat 2 tablespoons olive oil in large skillet over high heat. Add onion; sauté until dark brown and soft, about 5 minutes. Add chicken; sauté 2 minutes. Add 1 teaspoon salt, 1 tablespoon cumin, 2 teaspoons chili powder, and cinnamon. Sauté until chicken is cooked through, about 3 minutes longer.
Arrange lentils on large platter. Place sliced chicken atop lentils. Drizzle with remaining dressing and sprinkle with parsley.