One of my favourite meals to cook when I've been eating badly for a day or two is this simple, flavourful vegetable soup. It's versatile, requires minimal effort and preparation, and will last you a couple of lunches if you make a big pot - very handy for taking in to work or when you're too tired (lazy) to whip something up.
Canned chopped tomatoes (I try to find organic brands without citric acid)
Whatever other vegetables you have lying around! I often use celery, carrots, cauliflower and sometimes, for a more filling but ever so slightly carb-y rendition, potatoes.
Don't bother with measurements - do it all to taste. Add a small amount of water to the soup and season with black pepper, salt, herbs, garlic powder and a dash of ginger. Bring to boil, then simmer for an hour.
Sprinkle some chopped spring onions on top, add a dollop of fat free greek yoghurt and you're done. Yum.