Preheat the oven to 200C/400F/Gas mark 6.
Use scissors to cut up the tortilla into pieces the size and shape of tortilla chips, and spread across a baking tray. Bake in the oven for 5 minutes until slightly golden and crispy. Leave to cool on the baking tray.
Heat a splash of oil in a medium (preferably non-stick) frying pan over a medium heat. While the pan is heating up, thinly slice the red onion and radish. Fry the onion until soft. Add 4 teaspoons of the salsa and cook for about a minute, before stirring in the black beans.
Add the baked tortilla chips to the pan and stir in as much as you can until the tortilla chips are partially coated in salsa and beans and they have started to go soft in a few places.
Make a shallow well in the middle of the pan and crack in the egg. Cook for about 5 minutes until the egg is set. Season the whole pan with salt and pepper and drizzle with the remainder of the salsa. Scatter with fresh coriander and sliced radish and slide the contents of the pan onto a plate. Serve with sliced avocado and a fresh lime wedge on the side.