When I'm not in the mood or don't have the time to cook an elaborate dinner, my go-to meal is usually a sandwich or a salad (or takeout). I love tuna salad sandwiches. My favorite canned tuna from the supermarkets are Genova Tonno in Olive Oil and Progresso Light Tuna in Olive Oil - both taste fresher and less canny than other brands. I hear Pastene's is also good, but I haven't tried it.
I love adding red onions and fresh lemon juice to tuna. I drain most of the olive oil but keep enough to minimize the need for too much mayo. I add a touch of mayo to help bind the whole thing together - I prefer a much lighter salad so I go heavy on the lemon juice. Unless I'm using Genova Tonno in Olive Oil (it's much saltier than Progresso) I add a pinch of salt and black pepper. If I'm not being lazy, I also like to add fresh chopped parsley and capers (use less salt if adding capers).
I scoop out some of the bread to make room for the tuna then pre-toast/bake for a couple of minutes (without tuna) - this way the bread doesn't end up soggy.
Finally, I like to top it all off with extra love - grated cheese. I prefer cheddar. Back in the oven until the cheese starts to bubble.
Don't forget the chips/crisps. Eating chips with a tuna sandwich takes me back to my brown bag lunch days. Now only if I can get my hands on a carton of Hi-C or CapriSun.