Heat oil in a Dutch oven (or other 5-quart pot) over medium-high heat. Add onions, bell pepper, thyme, 1 1/2 teaspoons salt, and 1/4 teaspoon pepper. Cook, stirring occasionally, until onions begin to brown, 4 to 5 minutes.
Stir in tomato paste; add chicken, tomatoes, Worcestershire sauce, and 1 1/2 cups water. Bring to a boil; reduce to a simmer. Cover, and cook until chicken is opaque throughout, about 15 minutes.
Remove chicken from pot; stir in corn and lima beans, and simmer until heated through, about 5 minutes. Meanwhile, shred chicken meat with your fingers or a fork. Return chicken to pot, and stir to combine.