1: Mix the flour and yeast together in a large bowl and make a well in the centre. Gradually whisk in the milk to form a batter. Cover with clingfilm and leave for 1 hour at room temperature until slightly bubbly and aerated.
2: Meanwhile, make the seaweed salt. Break the seaweed sheet into a food processor and pulse a couple of times. Add the sea salt and pulse a few more times until well blended together. Leave to one side until needed.
3: To make the seaweed mayonnaise, first pick over the gutweed and rinse it well, making sure you get rid of all dirt and any grit, then squeeze it dry. Place it in a food processor with the rice wine vinegar, egg yolks and wasabi paste and blend. With the motor running, slowly add the oil until it emulsifies and thickens. Transfer to a bowl, cover and chill until needed.
4: Open the oysters and strain off the liquid. When you are ready to deep-fry the oyster fritters, heat enough oil for deep-frying in a deep-fat fryer or a heavy-based saucepan until it reaches 180°C.
5: One at a time, dust the oysters in flour and shake off the excess, then dip them into the batter, letting the excess drip off.
6: Deep-fry the oysters for about 2 minutes until golden brown. Use a slotted spoon to remove them from the oil, drain well on kitchen paper, then season with the seaweed salt.
7: Serve immediately with the mayonnaise and lemon wedges for squeezing over.