Combine tomatoes, basil, garlic, vinegar, 1/2 tsp of salt, 1/8 tsp of pepper.
Sprinkle the salmon with cumin and remaining salt and pepper. heat oil in nonstick skillet over medium-high heat. add the salmon and cook 4 minutes. Turn salmon and cook 1 minute longer. Cover the pan, reduce heat to medium and cook until the salmon is just opaque in the center and flakes easily, 2-3 minutes.
Transfer salmon to serving plates and add the tomato mixture to skillet. Increase the heat to high and cook until the mixture is warm, 1-2 minutes. Spoon relish over the salmon.