Choose a new cookbook worth up to £28 when you subscribe to our magazine.
Roughly chop the sorrel, tip into a food processor with the butter and lemon juice, and whizz to a paste. Season, scrape onto a sheet of cling film and roll into a log. Will keep in the fridge for one week, or in the freezer for a month.
Cook the pasta following pack instructions until al dente. Meanwhile, put the sorrel butter in a large frying pan to melt and, using tongs, add the pasta straight from the water and toss in the butter. Add most of the pine nuts and mix well before twirling the pasta into bowls. Scatter with parmesan and the remaining pine nuts, and serve immediately.