Heat the oil in a large, deep skillet or Dutch oven over medium heat. Add the red and green bell peppers, celery, carrots, and garlic and cook, stirring occasionally, until beginning to brown, about 8 minutes.
Stir in the smoked paprika, chili powder, salt, and cayenne. Cook, stirring, for 30 seconds. Working in small handfuls, stir in the kale, stirring after each addition to let it wilt slightly before adding another handful. Cook and stir until you can fit all of the kale in the pot.
Add the black-eyed peas and tomatoes with their juices. Stir and continue to cook until heated through, about 2 additional minutes. Taste and add additional salt or spices as desired. Serve hot with rice and a sprinkle of green onion.