Hearty Lentil and Root Vegetable Stew

1 cup dried red lentils, rinsed and sorted

1/2 cups cubed turnip (1 inch)

1 medium onion, cut into 1/2-inch wedges

2 medium carrots, cut into 1-inch pieces

1 medium red bell pepper, cut into 1-inch pieces

1/2 teaspoon dried oregano

1/8 teaspoon red pepper flakes

1 tablespoon olive oil

1/2 teaspoon salt

4 slices bacon, crisp-cooked and crumbled

1/2 cup finely chopped green onions