Nando's Portuguese Chicken Burgers

Name: Nando's Portuguese Chicken Burgers
Prep time: 15 min
Cook time: 15 min
Total time: 30 min
Cuisine: Portuguese
Ingredients: 1 - 3 birds eye red chilies ((1 is mild, 3 is reasonably spicy) (Note 1)); 1 large red bell pepper/ capsicum (, cut into chunks); 5 garlic cloves; 3 tbsp vegetable oil; 4 tbsp malt vinegar (, or any other plain brown vinegar except not balsamic); 2 tbsp paprika; 1 tbsp dried oregano; 2 tsp onion powder; 1 1/2 tsp white sugar; 1 1/2 tsp salt; Black pepper; Few drop of red food colouring ((optional)); 3 tbsp Peri Peri Sauce; ½ cup whole egg mayonnaise; ¼ cup sour cream ((or yoghurt)); 1 tbsp olive oil; 4 chicken thigh fillets (, skinless boneless (each large enough for a burger)); 4 soft rolls; 2 tomatoes (, sliced); Lettuce of choice