Improvisation is great, but recipes can be a guide to temperature, quantity and cooking times – and don’t underestimate the virtue of a sheet of foil

Whenever I make a marinade for fish or meat (usually invented and based on what I have in the cupboard ), it often burns when I cook the dish in the oven. How can I avoid this? Tatiana, Strasbourg, France

Speaking as someone who is in the recipe-writing business, it would be remiss of me not to suggest that you consider following one, even if only loosely. That aside, I’m all up for invention and using what you have.