Heat oven to 200C/180C fan/gas 6. Toss the sweet potatoes with the paprika and 2 tbsp olive oil in a roasting tin. Roast for 15 mins, tossing halfway through, until the potatoes are beginning to crisp.
Stone, peel and chop the avocado, tip into a bowl with the lime juice and zest, and season generously. Mash together with a fork and set aside. In a small bowl, combine the peanut butter and remaining olive oil. Set aside.
Heat a griddle pan or frying pan over a medium heat until very hot. Brush each tortilla on one side with the remaining oil. Place one tortilla, oiled-side down, in the pan and spread over half the peanut butter mixture, half the sweet potatoes, a little chilli sauce and half the coriander. Top with another tortilla, oiled-side up. Press down with a heavy saucepan and cook for 2-3 mins each side until the quesadilla is crisp outside and warm in the middle. Repeat to make a second quesadilla, then cut each into quarters and serve with the crushed avocado and lime wedges.