Venison Burger with Port, Bacon & Baked Red Onions

Ingredients

• 2 medium sized red onions, cut into small wedges (each ½ cut into 3-4 pieces)
• 50ml of 3-year-old balsamic vinegar
• 30ml olive oil
• 30g brown sugar
• ½ tsp chopped thyme
• 1 tsp coarse sea salt
• 8 turns of milled black pepper
• 2 large pinches of Herb de Provence or dried mixed herbs
• 500g venison meat, minced
• 100g pork fat, minced
• 6g salt
• ½ tsp of fresh thyme leaf
• Large pinch of ground nutmeg
• Pinch of mixed spice
• 3 banana shallots, finely chopped
• 2 cloves garlic finely chopped
• 250ml of port, reduced to 50ml
• 2 egg yolks