Heat oil in a frying pan over medium-high heat. Cook onion, stirring occasionally, for 5 minutes until softened. Add garlic, cumin, ground coriander, and paprika Cook, stirring, for 1 minute or until fragrant. Add beans and 1/3 cup water. Season with salt and pepper. Simmer, stirring occasionally, for 5 minutes or until mixture thickens and liquid has evaporated. Remove from heat. Stir in lime juice and chopped coriander. Toss through tuna.
Preheat oven to 180 degrees C.
Arrange half the tortilla chips in a baking dish. Sprinkle with ½ cup cheese. Top with remaining corn chips, tuna mixture and sprinkle with remaining cheese. Bake for 15 minutes or until cheese has melted and tuna is heated through.
Sprinkle nachos with tomato and avocado. Dollop with sour cream and top with jalapeño, coriander sprigs, and spring onions. Serve with lime wedges.