Preheat the oven to 425 F
Cut the cauliflower into small florets. Add them to a large baking sheet and toss with 1/4 cup olive oil, 2 tsp za'atar seasoning and salt & pepper.
Roast for 35 minutes, flipping halfway through, until browned and tender.
While the cauliflower roasts, heat a pot on medium heat with 1 tbsp of olive oil. Add the dry pearled couscous and toast for 1-2 minutes. Add in a pinch of salt and 2 1/4 cups water, cover the pot and bring to a boil. Once boiling, reduce the flame to low and simmer for about 20 minutes, until all of the liquid is absorbed.
Trim the ends off of the leeks and rinse well, then slice into rounds. Heat a skillet on medium heat with 3 tbsp of olive oil. Saute the leeks for about 10-12 minutes, until browned and caramelized.
To prepare the dressing, add all of the dressing ingredients to a blender and blend until smooth, or blend together using an immersion blender.
Assemble the salad by adding the pearl couscous, roasted cauliflower, sauteed leeks and feta cheese to a bowl or platter. Top with the dressing and toss together.
Garnish with fresh dill when serving.