Season thighs and legs with salt and pepper. Heat olive oil to medium high heat in a large flat bottom sauté pan until hot and shimmering. Brown chicken pieces, flipping halfway through, about 7-10 minutes a side. Remove chicken from heat. Add onions, garlic, sage, tomatoes, and tomato paste, also scraping up any chicken renderings sticking to the bottom of the pan. Season with salt and pepper. Cook, stirring infrequently, until onions are translucent, about 5-7 minutes. Add cup of water and white wine vinegar, stir to mix with onions. Add back in chicken pieces, dredge chicken with the sauce, season with salt and pepper. Bring sauce to boil. Cover, turn heat down to low, and let simmer for 15-20 minutes. Add in green olives and peas, gently stir to mix. Cover pan again, unless sauce is too watery, then leave uncovered, and let simmer another 15-20 minutes.