You need:
20 large red claws, halved & cleaned
1 lemon, juiced
250g butter, diced
2 cloves garlic, finely chopped
1 large red chilli, seeded & finely diced
1 tbs each parsley, dill, chervil, finely chopped
Salt & pepper

Method:
Place lemon juice in a pot, place over high heat & reduce by half. Lower heat & whisk in butter piece by piece until emulsified. Add garlic, chilli and herbs.
Season to taste & add more lemon juice if required.

For the crayfish, you could also substitute prawns, moreton bay bug, scallops, marron etc..