Combine cucumber, red onion, vinegar, lemon juice, sugar, and salt. Toss and set aside.
Combine ground chicken, Greek yogurt, panko, and two tablespoons of the spice blend. Mix gently and form five patties. Refrigerate uncovered for 30 to 45 minutes.
Heat oil and 3 tablespoons butter in a saucepan. Add onion and cook until golden. Add ginger and garlic and cook for one minute. Add tomato paste and cook 2 to 3 minutes until deeper in color.Add remaining spice blend and stir for 30 seconds.
Whisk in the heavy cream and simmer for 6 to 8 minutes until thick enough to coat a spoon. Taste and adjust salt as desired. Remove from heat and whisk in the remaining tablespoon of butter, set aside and keep warm.
Heat a cast iron or stainless skillet over medium high. Sear patties 3 to 4 minutes per side. Once browned, cover and remove from heat to finish cooking (internal temp 165°F).
Lightly butter and toast buns. Optional - Mix melted butter with grated garlic and cilantro. Brush over the top buns.
Spread a spoonful of yogurt on the bottom bun, then add slaw. Place a patty on top of the slaw and spoon the warm butter sauce over the patty. Finish with cilantro, and butter glazed bun top.