Mix all the sauce ingredients in a bowl. Cover and set aside for 10 minutes in the fridge until ready to use.
Preheat oven to 350F.
Spread breadcrumbs on a baking tray. Spray with oil and bake for 3 - 5 minutes or until golden. Immediately transfer to a bowl.
Clean the tray and spray it with oil.
Cut fish fillets into equal square shapes that are just slightly larger than the buns.
In a medium bowl stir together the Batter ingredients.
Gently dip and coat the fish squares in batter and after that place them in the breadcrumbs and use your hands to delicately press them so all the sides are well covered.
Transfer to the prepared tray and repeat with the remaining fish.
Bake the fillets for 12 - 15 minutes or until the fish is cooked through.
After removing from the oven, immediately top with cheese so residual heat will semi-melt it.
Cut buns in half, and microwave for 20 seconds to warm through.
Top with the fish and cheese, and a good dollop of tartare sauce. Serve.
