Place the lentils in a pot. Add 3 cups water and curry powder. Cover the pot and bring to a boil. Reduce heat to medium and cook covered until lentils are tender, about 30-35 minutes. Drain and set aside.
Meanwhile heat 2 tablespoons olive oil in a frying pan over medium-high. Add the mushrooms and saute until mushrooms are golden and all liquid is absorbed. Add the turmeric powder and saute for 1-2 minutes.
Combine the lentils, mushrooms, green onion, cilantro and black olives in a large mixing bowl.
Whisk 2 tablespoons olive oil, 3 tablespoons balsamic vinegar, salt and pepper together in a small bowl. Pour the dressing over the salad and toss to coat. Serve at room temperature.