Finely grate the zest of 1 medium lime into a small bowl (about 1 teaspoon), then juice the lime plus a second as needed into the bowl until you have 3 tablespoons. Add 1 cup sour cream and ½ teaspoon of the kosher salt and whisk to combine to make the dipping sauce. Taste and season with more kosher salt as needed. Refrigerate until ready to serve.

Place ¾ cup all-purpose flour, 1 ¼ teaspoons baking powder, 1 teaspoon chili powder, and ½ teaspoon cayenne pepper if desired in the large bowl and stir to combine.

Prepare the following, adding each to the bowl of flour as you complete it: Shuck and cut the kernels from 4 ears fresh corn until you have 3 cups. If using frozen corn, measure out 3 cups thawed frozen corn kernels and drain well. Thinly slice 4 medium scallions (about ⅓ cup). Finely chop the leaves and tender stems from ½ medium bunch fresh cilantro until you have ½ cup. Crumble 5 ounces cotija cheese (about 1 cup). Stir to combine.

Place ¾ cup whole or 2% milk, 2 large eggs, and 1 ¼ teaspoons kosher salt in a medium bowl and whisk until combined. Add to the flour mixture and stir just until combined.

Arrange a rack in the middle of the oven and heat the oven to 200ºF. Fit a wire rack over a rimmed baking sheet.

Heat 2 tablespoons of the vegetable oil in a large nonstick frying pan or cast iron skillet (at least 12 inches) over medium heat until shimmering. Drop 4 (¼-cup) portions of the batter evenly around the pan. Cook until golden-brown on the bottom, 2 to 3 minutes. Flip with a flat spatula and cook until browned and cooked through, 2 to 3 minutes more. Reduce the heat to medium-low if the fritters are browning too quickly.

Transfer to the wire rack and place the baking sheet in the oven to keep warm. Repeat cooking the remaining batter, adding 2 tablespoons vegetable oil to the pan before each batch. Serve topped with the lime crema and sprinkled with more crumbled cotija cheese.