This is the month for cosy gratins, soups and casseroles. Making good use of the oven rather than the hob teases depth out of ingredients with crisp edges and extra layers of flavour. February’s home grown vegetables are mainly of the hearty root and brassica varieties: think swede, celeriac, Jerusalem artichokes, kale and Brussels sprouts. British fruit is harder to find but forced rhubarb is dazzling in both sweet and savoury dishes.