Sauce

1 tablespoon extra-virgin olive oil
6 garlic cloves, minced
1 large fresh red chile, minced
4 large plum tomatoes, chopped
1 tablespoon tomato paste
1/3 cup water
1 1/2 tablespoons chopped tarragon
Salt

Fish Cakes

3/4 pound Yukon Gold potatoes, peeled and cut into 1-inch chunks
1/4 cup instant polenta
1 1/2 pounds skinless cod or halibut fillets, cut into 1-inch chunks
4 garlic cloves, minced
2 tablespoons chopped parsley
2 tablespoons chopped cilantro
2 teaspoons kosher salt
1 1/2 teaspoons ground cumin
1 large egg, lightly beaten
1/2 teaspoon crushed red pepper
2 tablespoons canola oil