1. Preheat oven to 400°F. Toss beets with oil and cumin in bowl; season with salt and pepper, if desired. Spread beets on 2 baking sheets, and roast 30 to 40 minutes, rotating baking sheets halfway through and stirring beets occasionally.
2. While beets are still hot, transfer to large bowl, and stir in green onions and lemon juice.