For the pesto, whizz all ingredients in a blender, slowly pouring in the oil while blending until it forms a smooth, nutty paste. Season well and add a splash of water if it’s too thick. Set aside.
For the lemon mayo, mix all the ingredients together and season.
To make the batter, sift the flours together, then whisk, while slowly adding water. Continue until your batter is a thick but runny consistency. It should stick to your finger when you dip it in. Season.
Set a deep-fat fryer to 180C, or in a large pan filled no more than a third full, heat the oil until a piece of bread browns in 20 seconds. Meanwhile, check the haddock fillets for bones, season them and coat them in plain flour. Then dip each fillet in to the batter until each has a good coating. Place the fillets in to the deep-fat fryer or pan (make sure you give it a gentle shake so it doesn’t stick to the bottom). Cook until the batter becomes brown and crisp, around 4 mins. Remove and place on kitchen roll to soak up any oil.
To assemble, spread each tortilla with some of the pesto, then a tablespoon of lemon mayo. Add a handful of salad leaves and the cucumber, then top with the fish and more pesto. Season, wrap up and serve.