Season the chicken thighs with salt and pepper on both sides.
Heat up butter in a skillet over medium high heat. Add chicken skin side down and sear undisturbed for 6-7 minutes. Flip and cook for another 3-4 minutes. Plate it out and discard the skin.
Discard the excess fat from the skillet leaving about a couple of tablespoons. Add onions and sauté onions till they start turning brown.
Add in bell peppers and sauté till soft. Add in garlic and cook for a minute.
Stir in tomato paste and cook for a couple of minutes.
Remove from heat and stir in sweet Hungarian paprika and mix well.
Return back to heat and add in chicken broth and cook for a couple of minutes. Add chicken back into the skillet and cook, covered, for 40-45 minutes, until chicken is fall of the bone tender.
Place sour cream in a bowl and slowly mix in a spoonful of the hot paprikash sauce. Do it 4-5 times. This ensures the sour cream slowly comes to the temperature of the sauce and does not curdle, resulting in a smooth sauce. Mix this tempered sour cream into the skillet and mix well. I added an extra 1 tsp of sweet Hungarian paprika at this point too (optional). Taste and adjust the seasonings like salt and pepper.
Simmer on low heat for 8-10 minutes. Serve immediately.
