Sweet potato and coconut soup

Ingredients

• 3 large sweet potatoes
• 1 tbsp oil
• 1 red onion
• 4 garlic cloves (crushed)
• 2 tbsp curry powder
• 2 tsp ground cumin
• 2 tsp garam masala
• 1/2 tsp turmeric
• 1/2 tsp ground ginger
• 1/2 tsp chilli flakes
• 1 vegetable oxo cube
• 1 tin coconut milk
• 400ml water
• - salt and pepper