Cut the potato into cubes and place in a bowl alongside the spring onions, mayonnaise and dill. Season with salt and pepper and mix until well combined.
If you have a toastie machine, toast one side of the bread, turn it over and top the toasted side with the potato mixture, baby beets and sweetcorn, replace the lid, toasted side down, then pop back in the machine until crispy and golden.
If you don't have a toastie machine, warm the potatoes before adding them to the other ingredients and place between hot toast to make a sandwich.
