If you are using raw chicken breasts/thighs, start by browning the chicken in a large pot or Dutch oven in 1 Tbsp. olive oil. It doesn't have to be cooked completely through as it will continue cooking when you add to the stew.
If you are using the cooked chicken, pull the meat off the bones, shred, and set aside.
In the same pot you browned the chicken add 1 more Tbsp. olive oil, salt, pepper and saute the onion, carrot and celery for 3 minutes until the onion starts to get soft.
Stir in the white and sweet potatoes and red pepper and cook for 2 more minutes.
Add the garlic and deglaze the pan with 1/2 cup dry white wine.
Next, add 1 quart chicken broth and the herbs. Bring to a boil. Reduce heat to simmer and add the cooked chicken and roux. Stir well to completely incorporate the roux.
Cover and simmer for about 45 minutes. After 30 minutes add the frozen peas.
If you want to make the stew even thicker, shake vigorously 2 Tbsp. flour and 1/2 cup chicken broth in a tightly sealed jar until all lumps are dissolved. Add a little at a time until the stew is as thick as you'd like.