BLOOM: In a small bowl, add the saffron thread with 1 ice cube and allow the saffron to bloom as the ice melts.
MARINATE: In a medium bowl, toss the shrimp with the grated onions, saffron water, and kosher salt. Allow the shrimp to marinate for at least 15 minutes. Usually, I let it go for at least 2 hours covered in the fridge for best results, but this is optional.
MIX: In a 1 cup measuring cup add ¼ cup water, chicken bouillon, red pepper flakes, and ground sumac. Set aside for now.
DRAIN: Once ready to cook, drain the shrimp in a sieve and gently pat dry, but do not rinse.
COOK: Melt 1 tablespoon butter in a 12-inch cast iron or nonstick skillet (or larger) over medium-high heat. Once melted, add half the shrimp in a single layer and cook for 30-45 seconds undisturbed. You want the shrimp to start turning opaque before giving them another flip. Flip and cook the shrimp for another 20-45 seconds until they start to curl into a ‘c’ shape. Remove to a plate and cook the remaining shrimp the same way with another tablespoon of butter.
SAUCE: Add all the shrimp back to the pan, pour the prepared sauce over the shrimp. Once it starts to sizzle and evaporate, lower the heat to the lowest setting. Then add the remaining two tablespoons of butter in cubes and stir to slowly melt it into a thick sauce. Taste and adjust with salt as needed. Sprinkle with parsley if desired.
SERVE: Serve the shrimp with fresh basmati rice and a salad.