01 -
Heat 30 milliliters of olive oil in a large skillet or braiser over medium heat until shimmering.
02 -
Season chicken breasts evenly with kosher salt and freshly ground black pepper. Place them in the hot oil and brown each side until golden, then remove from the pan and set aside.
03 -
In the same pan, add sliced red onion, minced garlic, and mushrooms. Cook over low heat, stirring occasionally, until softened, about 7 to 8 minutes.
04 -
Pour in white wine and simmer until partially reduced and alcohol has evaporated, approximately 2 to 3 minutes. Stir in diced tomatoes, fresh thyme, fresh oregano, and sugar, combining thoroughly.
05 -
Return the browned chicken breasts to the pan, nestling them into the sauce. Bring to a gentle boil, then reduce heat to medium-low. Cover and simmer for 30 minutes, stirring occasionally.
06 -
After 30 minutes, stir the contents, adjust seasoning with salt and pepper as needed. Add unsalted butter pats and continue cooking uncovered for an additional 15 minutes, allowing the sauce to thicken and chicken to become tender.
07 -
Remove from heat and let rest for 5 minutes. Serve by spooning chicken and sauce into individual bowls.