Place the cooked and cooled buckwheat in a bowl and add the chopped spring onions.
Cut the cucumber in half lengthwise and scoop out the seeds with a spoon. Dice into small pieces and add to the bowl.
Cut the avocado and sun-blushed tomatoes into small cubes, then add them to the salad.
Pour over the lemon juice and olive oil, then season with salt and pepper to taste.
Gently fold everything together, then add the fresh herbs.
Let the salad sit for a few minutes before serving to allow the flavours to come together.