Heat the oil in a Dutch oven over medium heat. Add onion, green bell peppers, celery, carrots, and garlic. Cook, stirring occasionally, until beginning to brown, between 10-15 minutes.
Stir in the cayenne. Cook, stirring, for 30 seconds. Working in small handfuls, stir in the spinach, stirring after each addition to let it wilt slightly before adding another handful. Cook and stir until you can fit all of the spinach in the pot.
Add the black-eyed peas, tomatoes with their juices, parsley, apple cider vinegar, and liquid smoke. Stir and continue to cook until heated through and carrots are crisp tender.
Taste and add additional salt, pepper, or spices as desired. Serve hot over brown rice and a sprinkle of green onion.