Your culinary dilemmas, answered

Does it really matter if your tomatoes are not peeled, say, for a sugo or ratatouille?

The tomato is an ingenious vegetable. Or is it a fruit? Each part — skin, fruit wall, pith and that jelly-like stuff around the seeds — plays a different role in producing that tomato flavour. By removing the skin and the seed pulp, you get a drier, more refined tomato purée and you alter the sweet-acid balance of the flavour. I don't mind a bit of skin in a sauce, soup or ratatouille but it depends on the size of the tomatoes. This year, I've had a superabundance of golden cherry, which, as the name suggests, is not a giant; Roma were prolific too. Both are ideal for popping in the mouth and for adding a touch of class to a sauce or ratatouille. But peel them? Oh, spare me. Those massive, muscly varieties, though, such as Marmande, beefsteak and Cuor di Bue, of course I'd peel them. As for middle-sized varieties such as Tiger Tom, I'm not sure. It would depend on my mood.

Back in April, you said heating potatoes and vegetables removes the nutrients. I'd always assumed they went into the water, so use vegetable or potato water for gravy or cook them directly in the sauce. Are the nutrients just evaporating anyway?

The point of cooking vegetables is to soften them, to make them edible and easy to digest. You're bound to lose some nutritional qualities in the process, no matter how you cook them, because heat causes chemical reactions in the vegetable. Those lost nutritional elements don't just dissolve in the water, which you're adding to the gravy. There's no reason you shouldn't but you won't reclaim lost goodness. The quicker you can cook a vegetable, the better, but it's not quite as straightforward as that. It may be better to cook potatoes, say, below boiling point, so the outside and inside cook evenly. Steaming is a good way of cooking green vegetables, because they won't be bouncing around in boiling water, leaching flavour, colour and nutrients. Again, you can steam one layer of vegetables at a time if the steam is to surround and cook them; steaming also takes longer than boiling, because boiling water dissolves and extracts some pectin and calcium from the cell walls and steaming doesn't. The effectiveness of boiling can also depend on the hardness and pH level of the water — ideally, it should be soft and neutral or slightly alkaline. A little salt speeds up the softening process and reduces the level at which nutrients are leached out. Perhaps the best way to keep in minerals and vitamins is to chop vegetables small and cook them in a little water in a microwave.