In a small bowl of ice water add the diced red onion. (This will mellow the harshness of the onion). Let sit for about 5 minutes. Dry the onion well with paper towels.
In a small bowl, mix together the red onion, crème fraîche, 1 teaspoon lemon juice, 1/2 teaspoon salt, and a pinch of pepper.
In a large shallow bowl, toss the crab meat with 3 tablespoons of the crème fraîche mixture, the sugar snap pea slices, 1 tablespoon + 1 teaspoon lemon juice, 1 tablespoon extra virgin olive oil, and the parsley. Taste and adjust for seasoning.
Arrange 3 pancakes on 6 plates (or 18 on a large platter), top each pancake with a spoonful of the crab mixture. Arrange salad leaves around the plate and top each pancake with a dollop of the crème fraîche mixture. Drizzle with extra virgin olive oil and a squeeze of lemon juice.