Blend the breadcrumbs and almonds in a food processor until the mixture resembles breadcrumbs. Sprinkle the mixture onto a plate.
Sprinkle the flour onto a separate plate. Pour the beaten egg into a bowl. Dredge the fish first in the flour, then dip it into the beaten egg and water, and finally roll it in the breadcrumb and almond mixture.
Heat the oil and butter in a frying pan over a medium heat and fry the coated fish for 4-6 minutes, or until golden-brown and crisp on both sides and cooked through.
Serve the lemon sole with lemon wedges and tomato ketchup.