Sudanese sweet potato, spinach and peanut stew

Name: Sudanese sweet potato, spinach and peanut stew
Prep time: 10 min
Cook time: 35 min
Total time: 45 min
Cuisine: African
Ingredients: 1 tablespoon olive oil (or sunflower oil); 1 medium onion (finely chopped); 2 cloves garlic (finely chopped); 2 tablespoons tomato purée; 4 medium sweet potatoes (peeled and chopped into bite-size pieces); 400 g tinned chopped tomatoes; 500 ml boiling vegetable stock; 100 g shredded spinach leaves (fresh or frozen); 120 g peanut butter; Salt and pepper (to taste); chickpeas; vegan chicken-style pieces