This is a delicious salad anytime of year and it can also be turned into an appetizer bite!
Mix the vinegar and mustard with a whisk and slowly drizzle in the olive oil till the dressing is creamy and emulsified. Taste and season to taste- salt and pepper... more vinegar? It's up to your specific taste.
Prepare your endive leaves and chop, display as you want, mix in dressing just before serving, top with walnuts and roquefort cheese.