Preheat oven to 425 degrees. Trim and thinly slice scallions, separating whites from greens. Melt 1 TBSP butter in a small pot over medium-high heat. Add scallion whites and rice and cook for 30 seconds. Stir in stock concentrate and 3/4 cup water (11/2 cups for 4 servings). Bring to a boil, then cover and reduce heat to low. Cook until rice is tender, 15 minutes. Turn off heat; keep covered until ready to serve.

Meanwhile, pat chicken dry with paper towels. Season all over with salt, pepper, and half the Blackening Spice. Heat a drizzle of olive oil in a large pan over medium-high heat (use a nonstick pan if you have one). Add chicken and sear until browned, 2-4 minutes per side. Turn off heat; transfer to a baking sheet. Bake on top rack until cooked through, 7-10 minutes. Wipe out pan.

Wash and dry all produce. Core, deseed, and dice green pepper into 1/2-inch pieces. Dice celery into 1/2-inch pieces. Trim, peel, and dice carrot into 1/4-inch pieces. Dice tomato.

Heat a large drizzle of olive oil in pan used for chicken over medium-high heat. Add green pepper, celery, and carrot. Cook until slightly softened, 4-5 minutes. Add tomato, remaining Blackening Spice, salt, and pepper. Cook until softened and tender, 3-5 minutes more. TIP: If veggies begin to stick, stir in a splash of water.

Meanwhile, in a small bowl, combine sour cream, hot sauce (to taste), and a pinch of salt. Stir in water, 1 tsp at a time, until mixture reaches a drizzling consistency. Fluff rice with a fork, then stir into pan with veggies. Season with salt and pepper (to taste).

Transfer chicken to a cutting board, then slice crosswise. Divide rice mixture between bowls. Top with sliced chicken and drizzle with spicy crema. Garnish with scallion greens. Top with any remaining hot sauce, if desired.