Preparation Preheat oven to 325°F. Heat oil in large nonstick skillet over medium heat. Add salmon, skin side down; cook 2 minutes. Cover pan; cook salmon 2 minutes longer. Transfer salmon, skin side down, to baking sheet. Place in oven; cook until just opaque in center, about 8 minutes. Meanwhile, heat same skillet over medium heat. Add onion and next 3 ingredients; sauté until onion is golden, about 5 minutes. Stir in tomatoes, soy sauce, and sugar. Increase heat to medium-high and cook mixture until slightly thickened, stirring occasionally, about 3 minutes. Divide salmon among 4 plates and top with tomato sauce.
Preparation Preheat oven to 325°F. Heat oil in large nonstick skillet over medium heat. Add salmon, skin side down; cook 2 minutes. Cover pan; cook salmon 2 minutes longer. Transfer salmon, skin side down, to baking sheet. Place in oven; cook until just opaque in center, about 8 minutes. Meanwhile, heat same skillet over medium heat. Add onion and next 3 ingredients; sauté until onion is golden, about 5 minutes. Stir in tomatoes, soy sauce, and sugar. Increase heat to medium-high and cook mixture until slightly thickened, stirring occasionally, about 3 minutes. Divide salmon among 4 plates and top with tomato sauce.