Barbecue Beanburger Sliders

Sliders

• 1000 g water
• 60 g quinoa
• 60 g walnut halves
• 1 garlic clove
• 170 g red onions, quartered
• 10 g olive oil, plus extra for brushing
• 240 g tinned kidney beans, rinsed, drained (1 x 400 g tin)
• 100 g tinned black beans, rinsed, drained (drained weight)
• ½ - 1 Tbsp chilli powder, to taste
• ¾ tsp fine sea salt
• ¼ tsp ground black pepper

Barbecue Sauce

• 1 garlic clove
• 120 g tomato ketchup
• 2 Tbsp soft dark brown sugar
• 2 Tbsp Worcestershire sauce (see tip)
• 1 Tbsp cider vinegar
• 1 dash chilli sauce (e.g. Tabasco®)
• ¼ tsp mustard powder
• ¼ tsp fine sea salt
• 12 slider buns