Preheat the oven 220°C / 200°C Fan / 425°F / Gas mark 7.
Peal and cut sweet potatoes in 1 cm [0.4 inch] dice. Spread on a large oven tray, tossed with 3 Tbsp of olive oil and 1 tsp of smoked paprika. Cook for 20-25 mins until golden and soft. Season with a 1/4 tsp of salt.
In the meantime, make the black bean salsa. Rinse and drain the black beans and corn. Transfer to a bowl. Add fresh pineapple (cut into 1 cm [0.4 inch] dice), tomatoes (cut in halves), pepper (cut into 1 cm [0.4 inch] dice), red onion (finely diced) and crushed garlic clove. Add lime juice, ground cumin, ground coriander and chopped fresh coriander. Season to taste with salt.
To make the chipotle avocado sauce, place the avocado flesh into a blender. Add garlic clove, spices, chipotle, lime juice and half the water. Blend until smooth. Add more water until you get your desired consistency. Season to taste with salt.
When the sweet potatoes are cooked, pile them on each tortilla with salsa and avocado sauce. Sprinkle with more freshly chopped coriander if desired.