Chorizo, corn and chilli streusel muffins

Name: Chorizo, corn and chilli streusel muffins
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Cuisine: European, German
Ingredients: 225g (1 1/2 cups) self-raising flour; 50g (1/4 cup) polenta; 65g butter, chilled, chopped; 2 eggs; 185ml (3/4 cup) buttermilk; 100g mozzarella, cut into 1cm pieces; 1 sweet corncob, kernels removed; 3 spring onions (shallots), finely chopped; 1 chorizo, finely chopped; 1-2 small fresh red chillies, thinly sliced; 2 tbsp chopped fresh curly parsley; 2 tsp raw sugar; 30g mozzarella, extra, coarsely grated; Tomato, red onion & coriander salsa, to serve