Chicken gumbo

Name: Chicken gumbo
Ingredients: 1 tbsp olive oil; 500g skinless, boneless chicken thigh, cut into chunks; 1 onion, chopped; 1 green pepper, deseeded and chopped; 3 celery sticks, finely chopped; 1 garlic clove, finely chopped; ¼ tsp cayenne pepper; 1 tsp smoked paprika; 1 tsp ground cumin; 1 tsp dried thyme; 1 bay leaf; 1 heaped tbsp plain flour; 400g can chopped tomato; 400ml chicken stock; 100g okra, cut into 2cm rounds; small handful sage, leaves chopped; crusty bread or microwave rice, to serve