Place the avocado in a large bowl and use a fork to mash until almost smooth. Add the lime juice and chilli. Taste and season with salt and pepper. Spoon the avocado mixture into 2 small serving bowls and smooth the surface.
Combine the sour cream and taco seasoning in a medium bowl. Spread a thick layer of the sour cream mixture over the avocado mixture. Cover with plastic wrap and place in the fridge for 2 hours to set.
Combine the tomato and coriander in a small bowl. Taste and season with salt and pepper. Sprinkle the tomato mixture over the sour cream mixture to cover. Serve immediately with corn chips.
