Lamb and feta baguette

Ingredients

• 1 medium red onion, halved
• 550 grams lamb mince
• 1/3 cup finely chopped mint
• 1/2 teaspoon ground cumin
• 2 tablespoons tomato sauce
• 1 tablespoon vegetable or olive oil
• 1/2 cup bought hummus dip
• 1/3 cup sour cream
• 1 french breadstick (baguette), cut crosswise into 4
• 60 grams baby spinach leaves
• 1 medium tomato, sliced
• 1 lebanese cucumber, halved lengthwise, sliced thinly
• 100 grams feta, thinly sliced