Cod with Tomato Curry and Corn

Name: Cod with Tomato Curry and Corn
Ingredients: ½ tsp black peppercorns; ½ tbsp coriander seeds; ½ tsp fenugreek or white peppercorns; ½ tsp cumin seeds; 2 tbsp neutral oil; 1 large white onion, sliced thinly; 1 knob peeled ginger, about 2 oz., chopped; 4 garlic cloves, chopped; ½ tbsp ground turmeric; ½ tsp cinnamon; ½ tbsp kosher salt; 1 tbsp tomato paste; 1 stick plus 2 tbsp. unsalted butter; 3 lbs beefsteak tomatoes, chopped; 1 red jalapeño, sliced thinly; ½ cup crème fraîche; 4 ears of corn, shucked; freshly ground black pepper; 1 ½ lbs cod or other thick-fleshed white fish; olive oil