Preheat the oven to 200 C / fan 180 C / gas 6. Put the chilli powder, cumin, garlic salt and the 1 tbsp of oil in a large bowl.
While waiting for the oven to heat cut the potatoes into even size wedges and each piece of corn into 4. Toss the wedges and corn in the spice mixture and transfer into a roasting tray, and then the oven for 30 minutes, turning occasionally.
While waiting for the wedges to cook peel, stone and dice the avocado, chop the spring onion, coriander and quarter the tomatoes. Gently mix together with the lime juice and season to taste.
Around 5 minutes before the potatoes and corn are ready, boil a pan of water and drop the eggs gently into it poaching to your liking, or spray a pan with a light cooking spray and fry.
Serve the wedges and corn on plates, topping with the eggs. Add a sprinkle of white wine vinegar and the side of salsa.