Fish Bhuna (Bengali-Style Fried Fish in Onion and Tomato Curry)

Name: Fish Bhuna (Bengali-Style Fried Fish in Onion and Tomato Curry)
Total time: 45 min
Yield: 6
Ingredients: 2 small whole head-on dorade or other flavorful white-fleshed fish, cleaned (about 3 pounds total once cleaned; 1.4kg); see note; 2 teaspoons (8g) Diamond Crystal kosher salt, plus more to taste; 2 teaspoons (4g) ground turmeric; 3 teaspoons (6g) Kashmiri red chile powder (or 1 teaspoon cayenne pepper), divided; Neutral oil, such as canola, safflower, or peanut, for frying; 1 medium yellow onion, thinly sliced (about 10 1/2 ounces; 300g); One 2-inch piece ginger , peeled and grated (about 15g); 1 bay leaf; 1 tablespoon (8g) ground cumin; 2 teaspoons (4g) ground coriander; 1 1/2 cups cored and diced skin-on fresh tomatoes (12 ounces; 340g), from about 3 small tomatoes; 1 tablespoon (15g) distilled white vinegar; Freshly ground black pepper; Chopped fresh cilantro leaves and tender stems, for garnish