Courgette fries with spicy chilli mayonnaise

Method

1. In a large bowl, toss the courgettes with a large pinch of salt to coat. Tip into a colander set over the bowl and leave for 20 minutes (see Know-how).
2. For the mayonnaise, put the garlic, egg yolk, mustard and oil in a jug, then whizz using a stick blender until it emulsifies and thickens. Add most of the lemon juice, the chilli pesto and a good pinch of salt to taste, adjusting with a little more salt or juice if needed. Cover and set aside.
3. Put a deep-sided sauté pan or heavy-based pan over a medium-high heat and add 2-3cm vegetable oil. Heat to 180ºC on a digital thermometer (a piece of bread dropped into the oil should turn golden in 15-20 seconds).
4. Mix the flour in a large bowl with enough sparkling water to make a thin batter the consistency of double cream. Whisk the egg white in a separate bowl to soft peaks (that flop over), then fold into the batter. Pat the courgette batons dry with kitchen paper. Working in batches, toss the courgettes in the batter, then fry for about 1 minute until golden and crisp. Remove with a slotted spoon and drain on a plate lined with kitchen paper while you fry the rest.
5. Toss the hot courgette fries with salt flakes, lemon zest, parmesan and oregano, then serve immediately with the spicy mayonnaise.