Focus on your knifework to get thin slices of fluke for this light and refreshing no-cook meal.
Place four serving plates in refrigerator until well chilled, about 30 minutes. Using a sharp knife, slice fish fillet crosswise into very thin strips (about 1/8 inch thick). Arrange on the chilled plates, and cover tightly with plastic wrap. Return plates to refrigerator for 30 minutes.
Remove plates from refrigerator, and unwrap. Drizzle 1 teaspoon olive oil over fish, and evenly coat with a pastry brush. Season with salt and pepper.
Mix greens with mint and cilantro, and drizzle with remaining 2 tablespoons olive oil and half the lime juice. Season with salt and pepper, and mound salad mixture in the center of each of the plates over the fish. Sprinkle with remaining lime juice. Garnish with chopped herbs, and serve with toasted bread.
Fluke is another name for summer flounder; halibut, sole, or cod can also be used. When making sashimi, be sure to buy only the freshest fish possible from a reliable source.