For halibut:
4 (1 1/4-inch-thick) pieces skinless halibut fillet (about 6 ounces each)
1 cup whole milk
1/3 cup shelled pistachios (preferably Turkish), finely chopped
3 tablespoons cornmeal
3/4 teaspoon salt
1/4 teaspoon black pepper
1/4 cup extra-virgin olive oil

For spicy yogurt sauce:
1 cup thick Turkish or Greek yogurt (8 ounces)
1/2 cucumber, peeled, seeded, and finely diced (3/4 cup)
2 tablespoons chopped fresh dill
1 tablespoon finely chopped onion
1 tablespoon fresh lemon juice
2 teaspoons dried maras pepper
1/2 teaspoon salt, or to taste