Wash and dry all produce. Adjust rack to top position and preheat oven to 450 degrees. Remove and discard stems and large ribs from kale. Tear or chop leaves into 1-inch pieces. Halve, peel, and thinly slice shallot. Peel and mince 2 cloves garlic. Chop parsley until you have 1 TBSP. Cut potatoes into 1/2-inch cubes.

Toss potatoes with 1 TBSP oil, half the steak spice, salt, and pepper on a baking sheet. Roast in oven until crisp, 20-25 minutes, tossing halfway through.

Melt 1 TBSP butter in a large pan over medium heat. Add garlic. Cook until fragrant, about 30 seconds. Add kale and toss, then pour in 2 TBSP water. Cook, stirring, until tender, about 4 minutes. Remove pan from heat. Stir in half the sour cream and 1 TBSP water. Season with salt and pepper. Remove from pan and set aside, covered.

Heat 1 TBSP oil in same pan over medium heat. Pat steak dry with a paper towel and season all over with salt, pepper, and remaining steak spice. Add to pan and cook to desired doneness, 4-7 minutes per side. Remove from pan and let rest. Slice against the grain before serving.

Wipe out pan and place over medium-high heat. Add shallot and a drizzle of oil. Cook until softened, about 2 minutes. Stir in stock concentrates and 1/4 cup water. Simmer until slightly thickened, 1-2 minutes. Remove pan from heat and stir in 1 TBSP butter, half the chopped parsley, and remaining sour cream. Season with plenty of pepper.

Reheat kale in microwave, if needed. Divide steak, potatoes, and kale between plates. Drizzle pan sauce over steak and sprinkle with remaining chopped parsley.