Preheat oven to 425 degrees. First cook the barley, farro or quinoa.
In a small bowl, combine 1 teaspoon salt, sumac, paprika, and black pepper.
While you prep the cauliflower, add the pine nuts to a large rimmed baking sheet. Place in the oven tor 1-3 minutes until toasted, DO NOT BURN. Remove from the pan and set aside.
While the barley cooks, cut the cauliflower in medium florets if you haven't already. You want each floret to have a flat surface so they can roast properly on the pan. Add the cauliflower to a large bowl. Drizzle with two tablespoons plus two teaspoons of olive oil. Use hands to coat the cauliflower evenly.
Sprinkle the cauliflower with 1 tablespoon of the spice mixture. Use hands to evenly coat the cauliflower. Spread the cauliflower out flat side down on a large rimmed baking sheet. Make sure the florets aren't too close together. Roast in the oven for 20 minutes until they are caramelized on the bottom.
While the cauliflower is roasting, season the shrimp and make the tahini sauce. Add shrimp to the same bowl you use to coat the cauilflower in oil and seasoning. Add remaining tablespoon olive oil to the shrimp. Toss until coated. Sprinkle with remaining spice mixture. Toss until evenly coated.
To make the tahini sauce. Place all the ingredients in a blender. Blend until smooth. Add more water if you want a looser sauce. Season to taste with salt and pepper.
When the cauliflower has roasted for 20 minutes. Remove from the oven. Push the cauliflower to one side and add the shrimp to the empty side. Place back in the oven for five minutes or until shrimp are cooked through.
To assemble. Toss the warm or room temperature barley with spinach, 1/4 cup of the tahini sauce, and remaining 1/2 teaspoon salt. Season to taste with salt and pepper. Spoon some of the barley in a bowl. Top with cauliflower and shrimp. Drizzle with tahini sauce. Sprinkle with pine nuts. Garnish with extra cilantro.