Baked potato soup with saffron and Greek yogurt - Off a diet

Ingredients

• 2 cups potatoes (diced)
• 1 tbsp olive oil
• ½ tsp turmeric
• 3 tbsp olive oil
• 1 small onion (chopped)
• 1 garlic clove (crushed)
• 2½ cups vegetable stock
• ⅛ tsp saffron powder
• ½ cup Greek yogurt (low-fat, plus more for garnish)