Season the chicken with salt. In a large heavy-bottomed skillet that has a tight-fitting lid, melt the lard and butter together over medium-high flame. Brown the chicken well on both sides; then remove it to a plate.
Reduce heat to low and add the onions and garlic to the skillet and sauté for 1 to 2 minutes, until the onion just starts becoming translucent. Add in the tomato paste and paprika; stir well, and sauté on very low heat for another 30 to 45 seconds.
Pour in the diced tomatoes and chicken stock, raise the heat and bring to a boil. Then reduce heat and simmer, stirring occasionally to make a uniform sauce. Stir in the diced peppers. Taste. You may want to add more paprika—this needs to have a full pungent paprika-y flavor. Some recipes for this call for even more paprika than I use here.
Then return the chicken pieces to the pan, arranging them evenly, skin side up. Return the sauce to a simmer, cover the pan tightly, reduce the heat and cook gently for about 15 minutes (an instant read thermometer inserted into the thickest part of the thigh should say 165ºF.) To preserve the nice golden look of the skin, cook it skin side up the whole time and don’t turn it.
Once the chicken is cooked through, gently transfer it to a plate. Whisk together the flour, sour cream and cream; then add in a few spoons of the hot cooking liquid and whisk that together, this gradually warms up the cream mixture so it won’t break. Then stir it into the gently simmering sauce and whisk everything together. The sauce will slightly thicken—you don’t want hideous gloppy thickness, just something subtle and spoon-coating. Taste it and adjust seasoning with salt.
Return the chicken to the pan and heat it through. That’s it. Serve spooned over wide egg noodles or the carb of your choice.