Cut tofu into bite sized pieces and saute in 2 tablespoons oil until browned.
Meanwhile, in a small saucepan, saute garlic and green onions in remaining 1 tablespoon oil until garlic is golden.
Add water, orange juice, lemon juice, vinegar, soy sauce, brown sugar, and pepper flakes. Bring to a boil. Reduce heat to medium.
In a small cup or dish, mix together cornstarch and water until thoroughly blended. Pour cornstarch mixture into sauce, stirring constantly. Cook, stirring, over medium heat until sauce thickens to your liking. Remove from heat and combine with tofu until completely coated. Serve over rice.
Note: use more or less cornstarch mixture depending on how thick you like your sauce. You can also add ginger if you like that flavor. Or orange peel or orange juice concentrate for more orange flavor. Enjoy!