Start with the dressing by adding all the dressing ingredients in a jar, shake well and keep aside.
Place a medium pot filled with water on high heat and when it boils add the buckwheat. Simmer until tender but a bit chewy, about 15’, and place in a colander to strain. Keep aside in a large bowl.
Turn the oven on, air circulation at 190°C. Place in an oven-proof dish the cut veggies and drizzle with the oil. Sprinkle the thyme, season with the salt and pepper and cook for 40’ until tender and a bit charred. Remove from the oven and place in the bowl with the buckwheat.
To assemble the salad, take the bowl where the buckwheat and the veggies were added and add the olives, and most of the zaatar, pour the dressing and toss. Add the feta, sprinkle some more zaatar and serve.