By Guy Watson
This calls for quite few steps of preparation, but they can be done well in advance and once the lasagne is in the oven, you can sit back and relax. Red Russian is a little too delicate for this dish; curly kale or cavolo nero are ideal.
Heat the oven to 200°C/Gas 6.
Put the dried mushrooms in a heatproof bowl, pour over 100 ml hot water and leave to stand.
Heat the oil in large frying pan. Add the onion and f