Heat oil and add onions, garlic, jalapeno and sweet corn. Fry till it becomes soft. Add cajun spice mix and saute for 1-2 minutes. Remove from heat and allow to cool.
Drain the beans well and add to a big bowl. Mash the beans well. Add coriander, feta cheese, breadcrumbs, onion mixture, lime juice, pepper and salt.
Combine everything well. Line a tray with baking paper. Make 1/2 inch thick patties and place on the tray. Refrigerate for 1 hour.
Heat a pan and drizzle little oil. Cook the patties on medium-high heat for 3-4 minutes on each side or until golden.
For the sauce, mix avocado, sour cream, hot pepper sauce and season with salt.
Take a burger bun and halve it. Place some salad leaves and top it with tomato slices. Place a bean patty and place a dollop or two of the sauce.