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
1/2 cup vegetable broth or reduced-sodium chicken broth
1-2 teaspoons red Thai curry paste
1/2 pound green beans, trimmed and cut into 1-inch pieces
1 tablespoon brown sugar
2 teaspoons lime juice
1/2 teaspoon salt
1/3 cup chopped fresh cilantro
1 lime, quartered