**Cook the Chicken:**
- Heat the olive oil in a large pot or Dutch oven over medium-high heat.
- Season the chicken pieces with salt and pepper. Add the chicken to the pot in batches, cooking until browned on all sides, about 5-7 minutes. Remove the chicken from the pot and set it aside.
**Sauté the Vegetables:**
- In the same pot, add the chopped onion, carrots, and celery. Cook for 5-6 minutes, stirring occasionally, until the vegetables begin to soften.
- Add the minced garlic and cook for an additional 1-2 minutes, until fragrant.
**Build the Stew:**
- Stir in the tomato paste, cooking for 1 minute to coat the vegetables.
- Add the diced potatoes to the pot, then pour in the chicken broth and water. Stir to combine.
- Return the browned chicken to the pot, along with the thyme, rosemary, and bay leaves.
- Bring the mixture to a boil, then reduce the heat to low and cover the pot. Simmer for 30-40 minutes, or until the chicken is cooked through and the vegetables are tender.
**Thicken the Stew (Optional):**
- If you prefer a thicker stew, combine the flour with a few tablespoons of water in a small bowl, stirring to create a smooth slurry.
- Gradually stir the slurry into the simmering stew, continuing to cook for 5-10 minutes, until the stew has thickened to your desired consistency.
**Add the Peas:**
- In the last 5 minutes of cooking, stir in the frozen peas, allowing them to heat through.
**Serve:**
- Remove the bay leaves from the stew. Taste and adjust seasoning with additional salt and pepper if needed.
- Ladle the stew into bowls and garnish with chopped fresh parsley, if desired.
- Serve hot with crusty bread, rice, or on its own for a hearty, comforting meal.