1 medium (8-ounces) yellow onion, peeled, quartered, and root end trimmed
2 bay leaves
1 1/2 cups (9 1/2 ounces) dried field peas (cowpeas), preferably not black-eyed peas, rinsed, picked over for debris, and soaked overnight
1 tablespoon Diamond Crystal - for table salt use half as much by volume or the same weight
1/2 teaspoon freshly ground black pepper
1 teaspoon garlic powder
1 teaspoon onion powder
1 1/2 cups (10 ounces) uncooked parboiled long-grain white rice (see note)
In a 5-quart Dutch oven, combine ham hock, bay leaves, and quartered onion, and top with 3 quarts of water. Set over high heat, bring to a boil, then cook at a boil for 5 minutes. Reduce heat to maintain a gentle boil, cover with the lid slightly ajar, and cook until the ham hock is fork-tender, about 3 hours; top up with boiling water as needed to keep the ham hock covered. Discard bay leaves. Transfer ham hock and onion to a heatproof plate or bowl to cool. Measure 2 quarts (1.9L) broth and return it to the Dutch oven; save any remaining broth for another use. Pull ham hock meat and skin from the bones. Roughly chop up any larger pieces, then return meat, skin, and bones along with the onion to the pot. Drain field peas from soaking water, rinse, and add to the pot. Add salt, pepper, garlic powder, and onion powder. Set over high heat and return to a boil. Lower heat to maintain a gentle boil, cover with the lid slightly ajar, and cook until peas are al dente, about 45 minutes. About 15 minutes before peas are al dente, preheat oven to 350°F (175°C). Add parboiled rice to pot, stir to combine, then return to a full boil over high heat and cook for 1 minute, then turn off heat. Stir the pot well to incorporate the ingredients, cover fully with lid, and cook in oven for 30 minutes. Remove from the oven and let rest, covered, for 5 minutes. Fluff with a fork, and serve right away.