For the tartare sauce, finely chop the capers, cornichons and the parsley leaves, then mix with the mayonnaise, lemon zest and juice.
In a large, deep saucepan, heat the oil to 180ºC. If you don’t have a thermometer, carefully lower in a small piece of bread; if it bubbles to the surface, the oil is ready. While it’s heating, and while you’re cooking with it, always keep an eye on hot oil and be careful around it, as it can burn badly.
While the oil is heating, make the batter. Whisk the yolks into 350ml of iced water, then stir in the flours – don’t whisk till it’s completely smooth, you want a few lumps.
Add the oysters to coat, then gently shake off the excess.
In batches, carefully lower the oysters into the hot oil and cook till golden brown and crisp on all sides.
Remove with a slotted spoon, drain on kitchen paper, then sprinkle with paprika and sea salt.
To assemble your po’ boys, slice open the rolls, halve the tomatoes and peel the cucumber into strips.
Spoon tartare sauce on the bottom of your rolls, then add salad leaves, tomatoes and cucumber.
Top with the hot oysters, and spoon on a little more tartare sauce. Eat immediately, with a pint of cold Guinness.
