What to do with half a tin of chopped tomatoes
Chopped tomatoes come in 400g tins. Cooking for one, most recipes want about half of that. So every tin leaves a puddle of tomatoes and a small decision you did not ask for.
How long it actually keeps
Three or four days in the fridge, but not in the tin. Once it is open the metal is exposed, and tomatoes are acidic enough to take a metallic taste from it within a day. Tip the rest into a small container or a jar, put a lid on it, and it keeps perfectly well.
Five things to do with the rest
Make it the base of eggs the next morning
Simmer it with garlic and whatever spice is in the cupboard until it thickens, then crack eggs into it. That is shakshuka, and it uses exactly the amount you have left.
Turn it into a pasta sauce for one
Half a tin, a clove of garlic, a slug of olive oil, twenty minutes on a low heat. It reduces to about the right amount for one bowl of pasta.
Start a soup with it
Almost any tin of beans plus half a tin of tomatoes plus stock is soup. Blitz it or do not, depending on how the day went.
Braise something in it
Pour it over sausages, chicken thighs or a tin of chickpeas and put it in the oven. It does the work unattended.
Freeze it flat
In a freezer bag, pressed flat so it stacks and thaws in minutes. Frozen tomatoes are exactly as good as fresh ones out of a tin, because they were never fresh to begin with.
What not to do
Do not leave it in the open tin in the fridge, and do not tell yourself you will use it tomorrow without deciding what for. Half tins are the single most reliably wasted thing in a kitchen that cooks for one.
The better fix is not buying it twice
All of the above is damage limitation. The actual problem is that the pack was bought for one meal and nothing else in the week was planned around it.
That is what MealPlans4One does. It puts the rest of the pack into other dinners and says so on the ingredient itself. From a real plan:
half a 400g tin Tinned chopped tomatoes
Decant the other half into a small container and refrigerate; use it in meal 5 within 3 days.
The note tells you where the other half is going before you have even opened the tin. That is the difference between a recipe and a plan.
14 dinners for £19. First one free, on screen, before you decide.