Rinse chicken thighs and dry them lightly with a paper towel. With kitchen shears, trim excess fat. Sprinkle with salt, pepper, paprika and garlic powder to taste. Spread 1 1/2 cups flour on a plate or in a shallow bowl. Lightly coat each thigh with the flour, shaking off the excess.
Heat oil in a large cast-iron skillet or nonstick saute pan over medium-high heat. Add chicken; cook until browned on all sides. Don't worry about cooking through. Browning may be done in batches if necessary Remove chicken to a platter and set aside.
Scrape loose any browned bits that have stuck to the pan. Stir the remaining 1/4 cup flour into the pan juices and stir until mixture turns a rich, dark brown, scraping the pan to ensure that none of the chicken bits stick. Add onions and stir until they begin to soften. Slowly stir in chicken stock and simmer low for about 5 minutes, until the mixture just starts to thicken.
Return chicken to the pan, cover and cook for 15 to 20 minutes, checking once or twice, turning pieces and making sure the chicken isn't sticking. Cook until chicken is cooked through and tender. If needed, adjust seasoning with salt and pepper to taste and simmer uncovered for another 10 minutes.
Serve with rice or mashed potatoes.