Add the hazelnuts and cook for 2 minutes. Add the beans and lemon juice and cook for 2-3 minutes, until the beans are tender. Add the lemon zest, sugar, soy sauce and thyme and cook for 1 more minute. Add the lemon juice and stir constantly until the curd starts to thicken. Stir in the zest and butter, and keep stirring until the curd is thick.
Brits have it on toast, but it's great as a base for fruit tarts, etc.