Ingredients:
1 tablespoon olive oil, plus more for the grill
4 6-ounce tilapia fillets
1 teaspoon ground coriander
kosher salt and black pepper
6 radishes, sliced
1 cucumber, halved and sliced
2 tablespoons fresh lime juice, plus lime wedges for serving
8 corn tortillas, warmed
1 cup fresh cilantro leaves
1/4 cup sour cream