Heat oil in large non stick skillet over medium high heat. Cook onions for 2 minutes. Stir in garlic and ginger and cook for 30 minutes. Add in carrots. Cover and cook for 5 minutes. Stir in tofu and cook for 3 minutes. Add in baby corn and season mixture. In a small bowl, stir together soy sauce, vinegar, sugar and cornstarch. Add to skillet and bring to a simmer. When liquid begins to thick, stir in scallions and serve with rice.