Put the buckwheat and stock in a pan. Bring to the boil and cook for about 20 minutes until water has absorbed. Put a lid on and rest for 10 minutes.
In a small bowl, mix the olive oil, lime juice, paprika, cumin, chipotle paste and tomato purée.
Transfer the buckwheat to a serving bowl and add the dressing and garlic, if used, then mix well. Taste and adjust the seasoning.
Cut the salad onion, red pepper, avocado, tomatoes into small cubes. Add these to the buckwheat, together with the drained beans & chopped herbs, then toss gently.
Serve with Jalapeno slices if you like the heat.