In a large pot, heat oil over medium heat. Add celery, onion, green pepper and cook, stirring frequently for 7 to 8 minutes, or until onion is translucent. Add garlic and continue to cook for 1 minute or until fragrant.
Add soaked and rinsed black eyed peas, ham hock, chicken stock, water, bay leaf, thyme, Cajun seasoning, and salt. Stir to combine and bring to a boil, about 5 minutes.
Reduce heat, cover, and cook for 1 hour or until black eyed peas are tender.
Remove ham hock, take meat off the bone, shred it, and stir the meat into the soup. Stir in apple cider vinegar.
If needed, cook for an additional 15 minutes with cover off to thicken soup, as desired.
Serve in a shallow bowl with steamed white rice or sautéed greens, and garnished with sliced green onions.
If desired, substitute ½ pound bacon for the ham hock. Chop bacon into small pieces. Omit oil, cook bacon until almost crispy, and then add vegetables and continue as directed. Other options include sausage, ham, or smoked turkey.
Vegetarian option: Omit the ham hocks, substitute vegetable broth for the chicken broth, and add smoked paprika, to taste. Add a half teaspoon of liquid smoke, if desired, to replicate the flavor of the ham hocks.
Can't find black-eyed peas? They can be a little difficult to find, depending on the season and the region in which you live. Substitute another dried bean such as cranberry beans, navy beans, or pinto beans. Black beans would be fine, too, but be aware that the end product will be a different color.
Cajun seasoning substitute: ½ teaspoon paprika, ¼ teaspoon garlic powder, ¼ teaspoon cayenne or red pepper. This isn't exactly like the blend but it's pretty close. If you like things spicy, increase the amount of Cajun seasoning, or add red pepper flakes, or cayenne pepper.