A quick lunch needs to be a couple of things: substantial, tasty, pleasing to the eye and, most importantly, quick.
These open sandwiches really fit the bill. Made from Portuguese rolls that needs to be very fresh, cut open and liberally buttered. We have three toppings so with the easiest and quickest one we have a nice dollop of liver spread. It really is a great option with the fresh roll and creamy butter. If that is not an option for you, use fish spread that taste just as good in the combination.
The second option is the usual tomato and cheese: add thin slices crispy cucumber on the bottom, top with thin slices of cheese then fresh ripe tomatoes. Sprinkle with salt and pepper and that's it.
The last option is an interesting option: real Italian salami top with sweet and sour gherkins. It has a great texture combination (meaty and crunchy) as well as flavour (salty, sweet and sour) and always loved by the guys.
And there you have a quick solution that will feed at least 4 people for a light lunch.