Peel and slice a hard boiled egg OR make an omelette using salt and pepper.
Slice the tomato.
Wash and dry the lettuce leaves thoroughly.
Apply a thin layer of butter on both the bread slices.
Mix the tabasco sauce into the mayo, stir well and spread a thin layer of mayo on the butter layer.
Place the lettuce leaves, snugly tucked to fit the shape of the bread slice.
Place the sliced boiled egg or the omelette on top of this. Sprinkle a bit of salt and pepper if required.
Place the tomato slices on this. Spread some mustard sauce over this.
Cover with other slice of bread, mayo side down.
Tightly wrap in a cling wrap and carry in airtight container. This sandwich will keep good for 4-6 hours.