Bao buns with roast beef and sweet and sour onion

Ingredients

• 250 g of manitoba-type flour
• 70 ml of water
• 70 ml of milk
• 30 g of sugar
• 1 teaspoon of salt
• 1 tablespoon of seed oil
• 1 teaspoon of bicarbonate
• 2 tablespoons of apple cider vinegar
• 7 g of dried baking yeast
• For the roast beef with balsamic vinegar
• 600/800 g of beef for roast beef
• chopped herbs
• 5 tablespoons of Giusti 2 Gold Medals Balsamic Vinegar
• salt and pepper
• 1 clove of garlic
• extra virgin olive oil
• To complete the bao buns
• 6 large lettuce leaves
• mayonnaise
• 1 red onion
• hibiscus powder (to taste)
• white vinegar
• flaked salt