Place the milk, onion, peppercorns and bay leaf in a pot and heat to just before boiling point.
Remove from the heat and infuse for 30 minutes.
Pour the milk through a sieve.
In a saucepan melt the butter and then add the flour.
Stir until golden in colour.
Add one ladle of the milk and mix until smooth.
Add another ladle of milk and mix until smooth.
Add the rest of the milk and keep on a low heat for 30 minutes.
Add the cream and mix until smooth.
Remove from the heat and add the mustard and cheese.
While making your cheese sauce, lightly fry the mushrooms in the coconut oil.
Mix the mushrooms into the sauce.
Cook your crayfish and pour sauce over.
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