Adjust rack to top position and preheat oven to 450 degrees. Wash and dry produce.

Dice sweet potatoes into ½-inch pieces. Halve, peel, and cut onion into ½-inch-thick wedges. Roughly chop cilantro.

Toss sweet potatoes and onion on a baking sheet with a large drizzle of oil, garlic powder, salt, and pepper. Roast on top rack until browned and tender, 18-20 minutes.

Meanwhile, pat chicken* dry with paper towels; season all over with half the curry powder (you’ll use the rest in the next step), salt, and pepper.

Heat a drizzle of oil in a large pan over medium-high heat. Add chicken and sear until golden brown, 2 minutes per side (chicken will finish cooking in the next step).

Transfer chicken to a plate.

Add tomato paste and remaining curry powder to pan used for chicken over medium-high heat. Cook, stirring constantly, until fragrant, 30-60 seconds.

Stir in spinach, stock concentrate, sour cream, and ½ cup water (1 cup for 4 servings). Bring to a boil, then reduce heat to low.

Return chicken to pan. Cover and simmer until chicken is cooked through, 4-6 minutes.

Turn off heat; stir in 1 TBSP butter (2 TBSP for 4). Season with salt and pepper.

Meanwhile, in a small bowl, combine yogurt, half the cilantro, salt, and pepper. Add water 1 tsp at a time until mixture reaches a drizzling consistency.

Divide sweet potato jumble and chicken curry between shallow bowls. Top with cilantro yogurt and sprinkle with remaining cilantro. Serve.