Start this salad a day ahead since the beets need to marinate in the refrigerator overnight. Because it's easier to grate rind from whole fruit, grate 1/2 teaspoon orange rind before squeezing the fruit for juice.
Preheat oven to 350°.
Leave root and 1-inch stem on beets; scrub with a brush. Place beets in center of a baking sheet lined with aluminum foil. Drizzle with 1 teaspoon oil. Bake at 350° for 1 hour or until beets are tender. Cool completely. Peel and cut each beet into 8 wedges. Combine beets, onion, orange juice, 1/2 cup lemon juice, and 1 teaspoon salt in a large bowl. Cover and chill overnight.
Bring 1 cup water to a boil in a medium saucepan; add green beans. Cook 3 minutes or until beans are crisp-tender. Drain and rinse under cold water; drain. Place beans in a large bowl.
Drain beet mixture, reserving 2 tablespoons marinade. Add beet mixture to green beans, and toss gently. Combine reserved marinade, 1 tablespoon lemon juice, 1 tablespoon olive oil, grated orange rind, 1/4 teaspoon salt, pepper, and minced garlic in a small bowl; stir with a whisk. Pour marinade mixture over beet mixture; toss gently.