Put the buckwheat in a saucepan, cover with cold water and add a pinch of salt. Bring to the boil and cook for 10—15 minutes until still firm and not mushy. Drain under running cold water and remove the foam that accumulates. Drain again when cool.
Bring a large saucepan of lightly salted water to the boil and blanch the broccoli florets for 2—3 minutes. Refresh in cold water and drain.
Mix the cherry tomatoes with the buckwheat and broccoli in a large salad bowl. Slice the smoked salmon and add it to the bowl with the parsley and half of the dill.
Make the dressing by whisking the lemon juice and oil. Pour the dressing over the salad, mix lightly to combine and season to taste with salt and pepper. Serve immediately, garnished with the remaining dill.