In a small bowl, mash avocado with a fork until smooth.
In another small bowl, combine crab, 2 teaspoons cilantro, lime juice, onion whites, pinch of salt and pepper.
Spread avocado evenly over toast, top with crab mixture, radish, remaining cilantro, green onion, sprinkle of paprika, pinch of salt, pepper and a drizzle of olive oil. Cut in half and serve immediately.