1. In a bowl, add all the ingredient A and mix well. Set aside. This is your filling mixture.
2. Dredge Jerusalem artichoke in the flour, taking care to coat all sides and shake off any excess.
3. Combine 2 eggs with milk. On a slice of Jerusalem artichoke, place about 1 to 1.5 tbsp tuna filling mixture and spread. Cover another slice of Jerusalem artichoke on top and press down to make a sandwich!
4. Dip it in egg mixture, and finally coat it thoroughly with Panko (bread crumbs).
5. Put a tiny amount of panko to check if the oil is ready. If it sizzles, it's ready! (or stick a chopstick in the oil and see if bubbles start to appear around the chopstick). Remove excess panko from your 'sandwiches' and press them gently. Fry them both sides until browned.
6. Add the sauce ingredients into a small cup and mix to combine.