Blend the onions, parsley, and celery, garlic in a food processor or blender into a rough paste
Salt and pepper chicken, add about 2-3 tablespoons of the herb blend to the chicken. Set aside. You may do this step, ahead of time and let it marinate.
Preheat a Dutch oven or other large heavy pot over medium-high heat.
Add 2-3 tablespoons of oil to pot. Add the chicken, sauté for about 5-7 minutes chicken, turning once, until golden brown on both sides. Transfer chicken to a plate.
Pour all the mixture into the pot, scraping up any browned bits with a wooden spoon, stirring occasionally, for about 8-10 minutes. Add about ½ a cup of chicken stock if need be.
Mix the carrots, green beans and green peppers into the pot; let it simmer for 2 to 3 minutes. Adjust seasonings to taste. Turn off the stove.
Using a sharp knife cut both ends off the plantain. This will make it easy to grab the skin of the plantains. Slit a shallow line down the long seam of the plantain; peel only as deep as the peel. Remove plantain peel by pulling it back.
Cut plantains into rounds about an inch thick.
Heat up a large skillet or cast iron with oil up to ½ inch- medium-high heat until hot but not smoking.
Fry the plantains until golden brown, then toss plantains with medley of chicken and vegetables. Hold off, on this part, until you are ready to serve the meal
Serve immediately.