1 tablespoon olive oil, plus more for the grill
4 6-ounce tilapia, halibut, or black bass fillets
1 teaspoon ground coriander
kosher salt and black pepper
6 radishes, sliced (I omitted)
1 cucumber, halved and sliced (I diced)
1 diced tomato
2 tablespoons fresh lime juice, plus lime wedges for serving
8 corn tortillas, warmed
1 cup fresh cilantro leaves
1/4 cup sour cream
Heat grill to high; oil grill. Season the fish with the coriander, ½ teaspoon salt, and ¼ teaspoon pepper (and lime juice) and grill until cooked through, 1 to 2 minutes per side. Break into pieces.
In a medium bowl, toss the radishes and cucumber (and tomatoes) with the lime juice, oil, and ¼ teaspoon each salt and pepper. Serve the fish in the tortillas with the cucumber relish, cilantro, sour cream, and lime wedges.