Chilli Cornbread Pie

Name: Chilli Cornbread Pie
Ingredients: 1 tbsp. vegetable oil; 500 g lean beef mince; 1 large onion, chopped; 1 red pepper, chopped; 2 garlic cloves, crushed; 2 tsp. cumin; 1 tsp. ground coriander; 1/4 - 1/2 tsp chilli flakes, to taste; 1 tbsp. tomato puree; 2 tsp. dried oregano; 2 x 400 g tin chopped tomatoes; 400 g tin kidney beans, drained and rinsed; 300 mL buttermilk; 25 g butter, melted and cooled slightly; 2 medium eggs; 200 g polenta (not instant); 3/4 tsp. bicarbonate of soda; 100 g Cheddar cheese, grated