This dish makes a great side for roast beef or grilled lamb. Mirepoix is a popular flavour enhancer used in French cuisine. Normally, onion, carrot and celery are used but variations using other aromatic vegetables like garlic, mushrooms and sweet peppers are common in other cuisines. You’ll get the best results if you use an enamel-lined cast iron pot. Such vessels, made by quality manufactures like Le Creuset and Cuisinart, allow better heat distribution and less chance of scorching.