Heat the oil in a large deep pan and cook the spring onion over a high heat for 5 minutes, adding in the garlic, chilli and chipotle flakes for the last minute.
Add the tomatoes, mixed pulses, sweetcorn and 600ml water and bring to the boil. Stir in the crushed tortilla chips and cook over a medium heat for 10 minutes.
Squeeze in the juice of 1 lime and season with freshly ground black pepper. Serve in bowls with a spoonful of crème fraîche, the remaining tortilla chips, a wedge of lime and more freshly ground black pepper.