HOW TO MAKE DELICIOUS SANDWICHES
Sandwiches are very versatile and easy to make, and are great for a stand-alone dish or as appetizers, or as an evening tea snack. They can be made with many ingredients, and with different presentations. They can be hot, as hamburgers, or cold as a club sandwich. The different temperatures open for variations as well, since hot sandwiches can for example be enhanced by melted cheese, as in croque monsieur for example.
When you select a bread for sandwich making, you should think about its texture. Often, it is nice to have a tightly crumbed bread so you can slice it without much crumbling and unnecesary fuss. Usually white breads are better for this purpose, as the breads made of whole grains tend to crumble more. Of course, you don't have to care about it if you don't mind crumbling! However, in a restaurant, it is obvious that you want a 'luxury' feel to the sandwich with nice edges and all that esthetic stuff...
The thickness of the bread slice should not be too high - it should not give a dry feeling in the mouth, which it will if there is too much of it. Simply balance the filling and the amount of bread so it feels perfect in your own mouth. To make the breads more soft and moist you can toast them or brown them in oil or butter in a pan, as this will gelate the starch in the bread. And they will be warm, if this is what you want to get.
Then there are many breads that are not in the shape of loafs, but can be used for sandwich making anyway. For example tortillas, or pita bread, or maybe a focaccia can be something in your taste as well.
Besides the bread, a sandwich is also composed of spreads, fillings, and optionally, garnish.
Spreads are either in the form of butter, or something more exciting and less fat, for example mayonnaise, mustard, cream cheese or mascarpone, pesto or tapenade (Italian), guacamole, and also some fruit jams. One can also simply fry the bread in some fat in the pan to make it moist and lightly browned. The spreads should anyway protect the bread from the filling so the bread doesn't get soaked in water, and they also give the bread more moist and of course more flavor. Therefore, matching the spread to the rest of the sandwich is not so trivial - it should go well together with the other components. So, an Italian tapenade would call for a focaccia bread and some tomato-based filling, to give an example.
For the fillings, one thing that is really important is to dry them to the point that they will not soak the bread too much. The bread should have a flavor on its own and don't get soggy with e.g. mozzarella cheese liquid. Often, the fillings can simply be roasted or fried to get rid of some water, and simultaneously to get a nice flavorful browning on them. Obviously, this is easily done with sliced meats like turkey, ham, roast beef, etc. Vegetables can be roasted as well. Cheeses offer less chances of roasting, although they can be melted if appropriate. Such fillings don't need to be served hot, if you don't want to, but the roasting is good for the flavor and for the water content.
Lastly, garnishing a sandwich (or putting it between the two bread slices in case of a closed sandwich) is really simple, but the ingredients should match. Use lettuce, or veggies like tomato, peppers, marinated vegetables, sprouts, olives, or even fruits if appropriate. Then enjoy your delicious sandwich!