Mix the water, milk, eggs and spice powder well in a mug. Meanwhile fry the onion, garlic and ginger briefly and vigorously in a pan with oil. Then add the contents of the cup and mix a little in the pan with a spoon.
Do not stir any more, otherwise scrambled eggs will result. The omelette will be perfect when the egg mixture is firm and a firm, brownish edge has formed (approx. 5-10 minutes).
In the meantime, the tomatoes and baguettes can be heated in the oven at 175 ° for a good 5 minutes.
Halve the finished omelette, cut open the baguette rolls and top each with a slice of corned beef (you can also spread butter or margarine beforehand). Place a halved omelette on top, put the sliced tomatoes and fold the bread roll.