Preheat oven to 210C | 410F.
Lightly spray an oven tray with cooking oil spray; set aside.
Whisk the egg in a small shallow bowl.
Add in the flour, beer, garlic powder, salt and water.
Whisk slowly until all the ingredients come together; then beat until the batter is smooth.
Pat dry each prawn/shrimp until they are completely dry.
Holding the shrimp/prawns by the tail; dip one shrimp/prawn at a time into the batter to evenly coat; gently shake off any excess; then evenly coat them in the breadcrumbs.
Place them onto the oven tray in a single layer.
Bake them for 10 minutes on one side; flip them and bake for a further 8-10 minutes, or until cooked through (depending on the heat in your oven).
Combine all of the Teriyaki sauce ingredients into a small saucepan.
Bring to a boil; reduce heat and gently simmer until the sauce has thickened.
Divide the grated vegetables into each lettuce cup; place about 10 shrimp into each, tails removed; and drizzle with the teriyaki sauce.