While the grill is heating, mix together the sour cream, mayonnaise, cilantro, garlic, chipotle pepper, lime zest, lime juice, and 1/2 cup of the cotija cheese. Taste and season with salt, if needed.
1/2 cup Mexican crema, 1/2 cup mayonnaise, 1/2 cup chopped cilantro, 2 cloves garlic, 1/4 teaspoon chipotle pepper, 2 teaspoons lime zest, 2 Tablespoons lime juice, 1 cup cotija cheese