This is a Gordon Ramsey recipe for a very fresh tasting classic vinaigrette:
100ml Olive Oil
100ml Groundnut or preferably walnut oil
Juice half lemon
50ml sherry vinegar
1 heaped tsp caster sugar
A grind of salt and pepper.
Combine all ingredients together in an old jam jar or similar, and give it a damn good shake.
This vinaigrette is fabulous, it will keep in a glass jar in the fridge for quite a while.