Method:

1. Put the flour in a shallow dish and season with salt and black pepper. Pour the beaten egg with milk  into a strong zip lock bag. Put the breadcrumbs in a separate shallow dish.
2. Place each fish piece in the seasoned flour until lightly coated, then dip into the egg wash bag and gently toss. Then into the breadcrumbs until each piece is evenly coated. Put the prepared fish pieces on a plate.
3. Heat the oil in a deep heavy-based frying pan until a breadcrumb sizzles and turns brown when dropped into it. Add the fish fingers carefully and fry for 5–6 minutes, turning occasionally until golden brown and crisp on all sides. (You may need to do this in batches.) Remove the fish with a spatula and drain on kitchen paper.
4. Add 2 egg yolks, vinegar, Dijon Mustard, roasted garlic, salt & pepper and then blitz it up until your yolk turns bright yellow. Slowly add oil bit by bit, using water to knock it back if needed until oil is fully combined and mayo is glossy.
5. Thinly shred your lettuce.
6. Toast your thick cut white bread.
7. Then assemble the sandwich and enjoy.