Bring 3 1/2 cups water and 1/4 teaspoon salt to a boil in a saucepan. Gradually add the polenta, stirring constantly with a whisk. Reduce heat to low; cook 12 minutes, stirring occasionally.

Step 2

Combine tomatoes, onion, 2 tablespoons oil, vinegar, and capers.

Step 3

Heat a large nonstick skillet over medium-high heat. Add 1 tablespoon oil; swirl to coat. Sprinkle fish with 1/4 teaspoon salt and pepper. Cook, skin side down, 7 minutes; turn over, and cook 2 minutes. Remove from the pan.

Step 4

Add the tomato mixture to the pan, reduce heat to low, and cook 2 minutes.

Step 5

Spoon 3/4 cup polenta into each of 4 shallow bowls. Top each serving with 1 salmon fillet and 1/2 cup tomato mixture. Sprinkle each serving with parsley.