There's nothing in the fridge!
Well, I just had the same problem. I found a white onion, so I threw it in a pan to blacken it, then added some Tom Yam broth (Knorr cubes that I had), then topped it off with some old oaxacan cheese that was about to turn on me. Kind of a thai mex french onion. Interesting, to say the least. I actually enjoyed it - the flavor of the sweet carmelized onion with the tom yam ingredients were harmonious. The cheese sort of cut through the acidity and balanced it. Didn't have any bread.
As others stated, it does depend on your staple items. I generally have a well-stocked pantry and basic fridge items so my standbys:
Pasta w/ olive oil, garlic, and parmesan (fresh herbs if I have them)
Salad Nicoise w/ canned tuna, greens, hard-boiled eggs, olives, potatoes
Cheese souffle w/ simple green salad
Monte Cristo sandwich (ham and cheese sandwich dipped in egg and then pan-fried, dusted w/ powdered sugar, served w/ fruit jam)
Omelette or frittata served w/ bacon
Sesame soba noodles w/ frozen dumplings
Risotto w/ frozen peas and dried mint
I don't know what counts for staples, chez vous, but . . .
Assuming you eat carbs:
Tuna, pasta, cherry tomatoes or canned tomatoes, red pepper flakes, capers or chopped olives if you've got em. Voila! Puttanesca!
Pasta with pesto, potatoes and green beans is a favorite.
Pasta with frozen cauliflower (steamed), saffron, pine nuts/toasted nuts of your choice, and raisins/currants/chopped dried apricots.
Pasta with frozen cauliflower (steamed), mustard seed, thyme chopped green olives, and toasted bread crumbs.
Pasta with fresh lemon juice, butter, and freshly grated cheese. Lemon zest, thyme, or italian seasonings are a nice option.
Pasta with milk, butter, italian seasoning, and grated cheese.
Tuna salad with scrambled eggs and cheddar. Toast optional.
Grilled cheese and tomato soup made from pureed canned tomatoes and cream.
An omelette with whatever vegetables and cheese you have kicking around.
Salad nicoise inspired soup/stew: frozen green beans, chickpeans, canned tomatoes, tuna, oregano, red pepper flakes, olives or capers, and potatoes or pasta, baked in the oven, or served over polenta (if you have cornmeal in your pantry).