1. When boiling or steaming any green vegetable - put a couple of bayleaves in your saucepan - this will stop that awful boiled cabbage smell that seems to get everywhere!
2. Add a squeeze of lemon juice to the water when boiling your potatoes. This keeps them white and you wont have to add salt to the water either.
3. When hard boiling eggs - to keep them white (and not have the black rimmed yolk) - once they are hard-boiled - rinse them under cold water and hit them with the end of a knife to break the shell. This, I believe, will release a gas, and stop the yolks going black. Cool slightly, then peel off the shell.