Check your avocado is ripe before starting this recipe. (To speed up the ripening process, put the avocado in a paper bag with a banana and loosely close, then leave on the kitchen bench for a day or two.) Preheat a sandwich press (see cooking tip). Drain and rinse the beans.
Step 2 — Make bean filling
Put the beans in a large bowl and coarsely mash with a fork. Add the tomato paste, chipotle and Tex-Mex seasoning, lightly season with salt and pepper and stir to combine.
Step 3 — Prep avocado
Finely chop the spring onion. Coarsely mash the avocado in a bowl. Add the spring onion and 1 tbs white wine vinegar, season with salt and pepper and stir to combine.
Step 4 — Assemble quesadillas
Put 3 tortillas on a clean work surface. Divide the bean filling, half the spinach and the cheese among the tortillas, then sandwich with the remaining tortillas.
Step 5 — Cook quesadillas
Cook the quesadillas, in batches, for 2-3 mins until golden and crisp and the cheese is melted.
Step 6 — Get ready to serve
Pick the coriander leaves, discarding the stems. Drizzle the remaining spinach with 1 tsp extra virgin olive oil. Cut the quesadillas into wedges and divide among plates. Top with the smashed avocado and aioli. Scatter with the coriander leaves and serve with the dressed spinach.