1. 1. Sear the Chicken: Pat chicken pieces dry. Season with salt and pepper. Heat oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Brown chicken in batches until golden; do not overcrowd the pan. Remove chicken and set aside.

2. 2. Sauté Aromatics: Reduce heat to medium. Add chopped onion to the pot, cooking until softened, about 5-7 minutes. Stir in minced garlic and cook for another minute until fragrant.

3. 3. Add Paprika: Immediately remove the pot from heat. Stir in the Hungarian sweet paprika. This crucial step prevents the paprika from burning, preserving its sweet flavor.

4. 4. Deglaze and Simmer: Return pot to heat. Pour in chicken broth and diced tomatoes, scraping up any browned bits from the bottom. Bring to a gentle simmer.

5. 5. Return Chicken: Add the seared chicken back to the pot. Stir well. Reduce heat to low, cover, and simmer for 25-30 minutes, or until chicken is cooked through and tender.

6. 6. Thicken the Sauce: Meanwhile, in a small bowl, whisk together sour cream and flour until smooth.

7. 7. Finish the Paprikash: Gently stir a few tablespoons of the warm sauce into the sour cream mixture to temper it. Then, slowly pour the tempered sour cream back into the pot, stirring constantly. Simmer for another 5 minutes, without boiling, until the sauce thickens slightly.

8. 8. Season and Serve: Taste and adjust seasoning with salt and pepper as needed. Garnish with fresh parsley if desired.