Hugh and Leonora Rankin from Rankins, Sissinghurst provide us with a fennel sauce

1. Remove the green fronds from fennel and keep to one side. Dice the fennel and onion and sweat in 50g butter until soft.
2. Add a splash of Pastis and either flame to remove alcohol or boil for 20 seconds or so.
3. Stir in the grated lemon zest and crème fraîche.
4. Pour the contents of the pan into a blender and blitz. Loosen with water or stock if needed.
5. Return to the pan, bring to the simmer and add 100g butter to the sauce, swirling the pan as you add the butter to give a single cream consistency.
6. Taste and adjust seasoning by adding lemon juice, salt and pepper. Chop the green fronds of the fennel and serve artistically atop your chosen dish.