Austrian Potato Salad

• 1 kg type B or C potatoes, quartered, cut into 1/4-inch-thick slices
• 2 tbsp white wine vinegar
• 1/4 cup olive oil
• 2 tbsp Dijon mustard
• 1 small red onion, minced
• 1 bunch minced chives
• 1/2 cup stock
• freshly ground black pepper

Bring potatoes to boil in salted water, then simmer until cooked but still firm, about 6 minutes. Strain and immediately sprinkle with vinegar, stir. Let cool for a bit. Add remaining ingredients and stir well until the salad thickens. Cool down completely and let rest in a fridge overnight.