Add ginger, coriander powder, vegetable stock. Then add the potatoes. Mix it properly and add pepper and lemon. Mix again. You can optionally cook it for another 3-5 min to make the potatoes go crispy.

Take a toast bread and put some of this potatoes mix on top. Then put a slice of cheese. Then take the second bread and put some sauce on it. Then put it on top of the cheese to close your sandwich. Now just apply some butter on top and grill it.