Heat butter and oil in a large saucepan and fry chopped onions until soft.
Add 400g peas and cook for 3 to 4 minutes.
Pour boiling stock over the vegetables, return to boil, and cook until peas are tender.
Drain the mixture, reserving a small amount of liquid.
Blend peas and onions in a food processor with a little reserved stock.
Pass the puree through a sieve and cool in a bowl over ice.
Mix diced olives, lettuce, herbs, citrus zest, and lime juice with crab meat.
Season the crab garnish with salt, pepper, and a little olive oil.
Place crab in rings at the center of shallow bowls and pour soup around it.
Top with a whipped cream quenelle, extra olive oil, and black pepper.