Red Curry with Vegetables

Name: Red Curry with Vegetables
Ingredients: 4 teaspoons canola oil, divided; 1 14-ounce package extra-firm tofu, rinsed, patted dry and cut into 1-inch cubes; 1 pound sweet potato, cut into 1-inch cubes; 1 14-ounce can lite coconut milk; ½ cup vegetable broth or reduced-sodium chicken broth; 1-2 teaspoons red Thai curry paste; ½ pound green beans, trimmed and cut into 1-inch pieces; 1 tablespoon brown sugar; 2 teaspoons lime juice; ½ teaspoon salt; ⅓ cup chopped fresh cilantro; 1 lime, quartered