Check your avocado is ripe before starting this recipe. (To speed up the ripening process, put the avocado in a paper bag with a banana and loosely close, then leave on the kitchen bench for a day or two.) Crush or finely chop the garlic. Finely chop the onion. Drain and rinse the beans and corn together. Preheat the grill to high.
Step 2 — Start bean mixture
Heat 2 tsp olive oil in a medium ovenproof frypan over high heat (see cooking tip). Cook the garlic, half the onion and a pinch of chilli flakes (omit if preferred), stirring regularly, for 3 mins or until softened.
Step 3 — Finish bean mixture
Add the beans and corn, tomato paste, Tex-Mex seasoning and 125ml (½ cup) water to the onion mixture and bring to the boil. Reduce the heat to medium and cook, stirring occasionally, for 2-3 mins until slightly reduced. Taste, then season with salt and pepper.
Step 4 — Make avocado salsa
Meanwhile, combine the remaining onion, 2 tsp extra virgin olive oil and 1 tsp red wine vinegar in a bowl and season with salt and pepper. Coarsely chop the avocado and gently stir into the onion mixture.
Step 5 — Assemble pie
Open the packet of corn chips and reserve half the corn chips for another use. Crush the remaining corn chips in the packet with your hands to form crumbs. Scatter the corn chip crumbs over the bean mixture in the pan. Scatter with the cheese and a small pinch of chilli flakes*, if desired.
Step 6 — Grill pie and serve
Grill the pie for 4 mins or until the cheese is melted. Serve the pie with the avocado salsa.