In glass container with lid, drizzle olive oil over fish. Crush garlic overtop and use brush to coat fish on both sides.
In small bowl, combine paprika, cumin, cayenne, and salt; sprinkle on both sides of fish.
Drizzle lime juice on both sides. Marinate fish, covered, in refrigerator for 30 minutes. Prior to cooking, remove from refrigerator and allow to come to room temperature.
Preheat oven to 375 F°.
Place fish on parchment-lined baking sheet. Bake for 4 minutes on each side.
While fish is cooking, in large saucepan, heat 1 tablespoon olive oil and sauté garlic and shallot on medium-low heat for about 2 minutes, or until soft and translucent. Remove from heat and set aside.
Bring 2 cups water to the boil. Add peas and pinch of salt. Cook peas for 4 to 6 minutes. Drain.
Use rubber spatula to scrape garlic, shallots, and olive oil into bowl of food processor. Add cooked peas, cilantro, serrano pepper, lime juice, and a further 1 tablespoon olive oil. Blend to a fine purée.
Toast or grill tortilla shells. Spread some pea purée onto each tortilla shell, top with fish, and garnish with sliced radishes and additional cilantro.
