for the chimichurri: In a food processor fitted with a metal blade, combine all chimichurri ingredients and process until a smooth paste forms. With a spatula, transfer chimichurri to a bowl and let stand at room temperature while preparing the soup, to let flavors blend.

for the soup: In a large pot (I use this one), heat oil and butter over medium heat. Add onion and sauté until it starts to soften, about 4 minutes. Add celery, garlic, and kosher salt. Continue to sauté until all vegetables are softened, about 4 to 5 minutes more.

Add whole pieces of boneless, skinless chicken thighs to the pot, along with chicken stock, white wine vinegar, bay leaf, and cumin. Bring to a boil over medium-high heat. Partially cover, reduce heat to low, and simmer gently until chicken is just cooked through. This should take about 20 to 25 minutes. Using tongs, transfer chicken to large plate and let cool slightly. Let soup sit, undisturbed, while shredding meat into bite-size pieces with two forks. If any scum develops on the surface of the soup, skim it off with a big spoon and discard.

Add shredded chicken back to the pot of soup, along with white beans, thyme leaves, and black pepper. Bring to a simmer over medium heat. Taste and adjust with additional salt and black pepper, if needed. Don't be afraid to add salt and pepper to amp up the flavor! Discard bay leaf.

Serve soup hot with chimichurri on the side, for individuals to swirl in as much as they please. Also offer chopped cilantro and sliced green onions for garnish.