Tamale Pie With Fresh Tomato and Corn

Name: Tamale Pie With Fresh Tomato and Corn
Ingredients: ½ pound fresh chorizo, casings removed (about 2 links), or vegetarian substitute; ½ pound ground beef, or vegetarian substitute; 1 tablespoon tomato paste; 2½ teaspoons cumin; 1 large onion, grated on a box grater, divided; 1–2 medium jalapeños, thinly sliced, seeded if desired, divided; 1¾ teaspoons kosher salt, divided; 2 large beefsteak tomatoes (about 2 pounds), cut into 1/2 cubes; 2 cups corn kernels (preferably fresh; from about 3 ears of corn), divided; 8 ounces cheddar cheese, grated (about 2 cups); 2 large eggs; 6 tablespoons unsalted butter, melted; ⅓ cup sour cream, plus more for serving; 1¼ cups cornmeal; 1 teaspoon baking powder