Drizzle the asparagus spears with the olive oil. Turn the barbecue to high heat or alternatively heat a large cast iron skillet or grill pan on high heat and once hot, place 6-8 spears of asparagus in the pan (you will have to work in batches to cook the asparagus so that they char evenly). Cook them for approximately 4 minutes until fork tender, turning them every minute or so to ensure they brown on all sides. Set the charred asparagus aside and continue cooking the remaining batches of asparagus until it is all cooked.
Add the dijon mustard and white wine vinegar to a bowl and whisk until smooth. Start by adding in 1 tbsp of olive oil, whisking continuously to help the mixture emulsify. Continue adding 1 tbsp of olive oil at a time while whisking until the dressing has thickened and become creamy in consistency.
Add the diced shallots, lemon zest, salt and pepper to the dressing and mix. Arrange the charred asapargus on a platter or serving plate and drizzle the dressing overtop. Garnish with the chopped chives and serve warm or at room temperature.