Melt the butter in a small saucepan. Add the onion and saute until starting to soften (about 2 minutes).
2 tablespoons unsalted butter, ½ cup minced onion (about ⅔ of a small onion)
Stir in paprika and and cook until fragrant (a few seconds).
2 teaspoons smoked paprika*
Add the chicken broth. Bring to a boil and cook, uncovered, until reduced by about half (3 to 4 minutes).
¾ cup chicken broth
Take off the heat and whisk or stir in the tomato paste.
1 ½ tablespoons tomato paste
Stir in heavy cream, sour cream and cilantro.
¼ cup heavy cream, 2 tablespoons full-fat sour cream, 2 tablespoons finely chopped cilantro
Turn the heat back on and heat the sauce through, stirring continuously.
Recipe notes:
*You can use smoked hot paprika for a spicy sauce or smoked sweet paprika for a milder sauce.Storage: Transfer any leftover sauce into an airtight container and store in the fridge. Reheat on the stovetop over gentle heat, stirring continuously.