Season the sole with salt and black pepper.
Heat a frying pan until hot and melt 25g of butter.
Cook the fish for two minutes on each side and keep warm.
Heat a separate pan and melt 25g of butter.
Fry the baby onions for five minutes until golden and tender.
Melt the remaining 25g of butter in a third pan with shallots and thyme.
Sauté for two minutes then reduce the white wine by half over high heat.
Add fish stock and reduce slightly before adding cream to simmer for 4 minutes.
Strain the sauce through a sieve and heat with the peas and sorrel until wilted.
Plate the sauce and fish topped with onions and serve.