sweet potato and black bean chilli

Ingredients

• 1 tablespoon olive or rapeseed oil
• Optional – 450g (1lb) of minced (ground) turkey thigh – ground breast is too dry for the long cooking here
• 1 large red onion
• 4 cloves garlic
• 3 fist sized sweet potatoes, left unpeeled but well scrubbed
• 2-3 teaspoons ground cumin
• 1-2 tablespoons sweet smoked paprika
• 2-3 teaspoons ground coriander
• 1-2 teaspoons ground cinnamon
• 1-2 teaspoons fennel seeds
• 1 teaspoon cocoa powder
• around 800g (28oz) canned diced salt-free tomatoes
• 1-2 cans of black beans, drained
• Juice and zest of 2 limes
• optional: 80g (half a cup) of un-cooked quinoa