At home I usually toast the bread on one side so that the inner bit is toasted before putting thin slices of cheddar and fine slices or chopped onion as the filling. Red onion for me gives it a slightly sweet taste which I quite like. I don't usually have toasted sandwiches when I am out on the basis that it is something I could do at home for the fraction of the price but thought I would try one for a treat in a Costa Coffee shop rather than spend on a cake. They do very tasty ones with a layer of toasted cheese on top which is very nice and looks appetising, one in particular has sausage, tomato and red onion which goes very well together as a filling. I have just bought a toasted sandwich maker and really happy that I can make a quick snack but I would like to experiment with sweet fillings or fruit for a change but would the sandwiches hold together as the cheese version?