Greek Submarine Sandwich

Ingredients

• 1 None medium red onion, halved
• 1 1/4 lbs ground lamb
• 1/3 cup mint, finely chopped
• 1/2 tsp cumin
• 2 tbsp tomato sauce
• 1 tbsp vegetable or olive oil
• 1/2 cup hummus
• 1/3 cup sour cream
• 1 None baguette, cut crosswise into 4
• 2 cups baby spinach leaves
• 1 None medium tomato, sliced
• 1 None lebanese cucumber, halved lengthwise, sliced thinly
• 3.5 oz feta, thinly sliced