Preparation

Cook the cotechino for 15 minutes, then let it cool down and cut it into 4 cubes.
Cover the cubes with puff pastry, then bake them for about 10 minutes at 170°C, until the puff pastry has become golden brown.
In the meantime, prepare the lentils (for dry lentils, soak them before cooking): stir-fry onion and rosemary with oil and salt, then add the lentils and cook for a few minutes.
Add two spoons of tomato purée and let it cook for 15/20 minutes, until the purée is well incorporated and lentils are cooked and soft.
To serve, cut the cotechino cube in puff pastry crust into halves, accompanying it with lentils and, possibly, decorating with fresh tomato cubes and mustard or salsa verde.