Place saffron threads into a small bowl and crush them up a bit with a spoon. Add 3 to 4 tablespoons of hot water and stir. Let bloom for about 10 minutes - the water should turn bright yellow/orange. Set aside.

Season chicken thighs on both sides with about 1 teaspoon salt and freshly cracked pepper.

Heat oil in a large nonstick skillet over medium-high heat. Add chicken thighs and sear on both sides until golden, 3 to 4 minutes per side. Remove and place on a plate to the side. Add onion to the same skillet and cook until soft and translucent, 3 to 4 minutes. Stir in garlic and curry powder and cook until fragrant, about 1 minute.

Pour in chicken stock and bring to a boil. Reduce heat to a simmer and add saffron mixture. Season with remaining 1 teaspoon salt and freshly cracked pepper. Stir to combine. Return chicken thighs to the skillet, cover, and simmer over low heat for 20 minutes, flipping thighs halfway through cook time. Season to taste and serve with the sauce.