1 gherkin, chopped
300g/10Β½oz fine green beans
Β½ shallot, finely sliced
1 sprig tarragon, leaves picked
100g/3Β½oz bag watercress, or a mix of peppery leaves
1 tsp English mustard powder
1 tsp Worcestershire sauce
salt and freshly ground black pepper
ΒΌ tsp freshly ground black pepper
Β½ tsp red wine vinegar
3 tbsp vegetable oil
handful of walnuts, roughly broken
1 tbsp walnut oil
500g/1lb 2oz venison fillet, at room temperature