Heat oil in a large straight-sided skillet over medium heat.
Season chicken with 1 teaspoon salt and 1/4 teaspoon pepper; cook, turning, until golden on all sides, about 10 minutes; transfer to a plate.
Add onion, garlic, 1 teaspoon salt and 1/4 teaspoon pepper to skillet; cook, stirring frequently, until onion is softened, 3 to 5 minutes.
Stir in rice, tomatoes, peppers, and 1 1/4 cups water; nestle chicken pieces in rice mixture.
Bring to a boil; reduce heat; cover, and simmer over medium-low heat until rice is tender, 55 to 60 minutes; if any liquid remains in skillet, remove lid and simmer until evaporated.
Sprinkle peas over contents of skillet; cover, and remove from heat; set aside until peas are heated through, about 10 minutes.
Serve with lemon wedges, if desired.