Sausage, pepper and tomato traybake

Ingredients

• 3 small onions, cut into wedges
• 1 red pepper, deseeded and sliced
• 1 yellow pepper, deseeded and sliced
• 250g cherry tomatoes
• 500g potatoes
• 6 garlic cloves, peeled but left whole
• 2 rosemary sprigs
• Low-calorie cooking spray
• 8 pork sausages
• 2 tbsp balsamic vinegar
• 1 chicken stock cube
• 300ml boiling water
• 1 tsp mixed herbs
• 2 tsp wholegrain mustard