In a large frypan, stir butter and a splash of olive oil over low-medium heat, until butter melts.  Add flour, stir until combined, then gradually add the stock, stirring as you add. 

Increase heat to medium-high, add French shallots, peas and broad beans, season generously.  Cover with lid and allow the peas to simmer until very tender.  Add lemon juice, zest, shredded mint and a little splash of olive oil, then season to taste. 

Serve lemony pea and broad beans with Boscastle Beef and Burgundy Pies.