Put the buckwheat, water and stock cube in a pan. Bring to the boil and cook for about 15-20 minutes until the water has absorbed. Put a lid on and rest for 10 minutes.
In a small bowl, mix the dressing.
Thinly slice the onion and drain the chickpeas.Cut the tomatoes in half.
Fluff the buckwheat with a fork, then transfer to a salad bowl.
Add the chopped herbs, tomato halves, onion slices and chickpeas, then mix well.
Add the dressing and toss well. Taste and adjust the seasoning.
Serve at room temperature.