In a shallow dish, whisk together the flour, cornstarch, paprika, garlic powder, onion powder, cayenne pepper (if using), salt, and black pepper.

In another shallow dish, whisk the eggs and milk.

Dip each piece of chicken into the egg mixture, then dredge it in the flour mixture, ensuring it's fully coated. Place the coated chicken on a plate.

Heat the vegetable oil in a large skillet or Dutch oven over medium-high heat until it reaches 350°F (175°C).

Carefully add the coated chicken to the hot oil in batches, being careful not to overcrowd the pan. Fry for 4-6 minutes per side, or until golden brown and cooked through. Remove the chicken with a slotted spoon and place it on a wire rack set over a baking sheet to drain.

In a medium skillet, melt the butter over medium heat. Add the corn and cook for 5-7 minutes, stirring occasionally, until tender and slightly charred.

Remove the skillet from the heat. Stir in the mayonnaise, crumbled cotija cheese, chopped cilantro, lime juice, and chili powder. Mix until well combined.

Warm the corn tortillas according to package directions (e.g., in a dry skillet, microwave, or directly over a low gas flame).

Fill each warm tortilla with a generous portion of fried chicken and the street corn mixture.

Garnish with extra cilantro, a squeeze of lime, and a dollop of sour cream or crema, if desired.

Serve immediately.