Season and sear the chicken. Pat the chicken dry and season with salt and pepper. Heat the oil in a large pot or Dutch oven over medium-high heat.
Sear the chicken in two batches until lightly browned, about 3–4 minutes per side. Transfer to a plate.
Sweat the aromatics. Reduce heat to medium. Add onion, carrots, and celery with a pinch of salt.
Cook, stirring occasionally, until softened and lightly golden, 6–8 minutes. Stir in the garlic and cook 30 seconds, just until fragrant.
Build the base. Add the tomato paste and cook, stirring, for 1 minute to caramelize it. Sprinkle in the flour and cook another minute, stirring to coat the vegetables.
This helps thicken the stew later.
Deglaze and simmer. Gradually pour in the chicken broth while stirring to remove any browned bits from the bottom of the pot. Add the potatoes, bay leaf, thyme, rosemary, and soy sauce or Worcestershire if using. Return the chicken and any juices to the pot.
Simmer until tender. Bring to a gentle boil, then lower to a simmer.
Cover partially and cook 25–30 minutes, stirring occasionally, until the potatoes and chicken are tender and the broth has thickened.
Finish and brighten. Stir in the vinegar or lemon juice, peas, and parsley. Simmer 2–3 more minutes. Taste and adjust seasoning with more salt and pepper as needed.
Serve. Ladle into bowls and enjoy as is, or spoon over rice, mashed potatoes, or buttered noodles.