Rinse and sort through 1 lb dried red kidney beans, removing any debris. Cover with water by 2 inches in a large pot, bring to a boil for 2 minutes, then remove from heat and soak for 1 hour. Drain and set aside.

Dice 1 large yellow onion, 3 celery stalks, and 1 green bell pepper. Mince 4 garlic cloves. Slice 1 lb andouille sausage into 1/4-inch thick rounds.

Heat 2 tbsp vegetable oil in a large Dutch oven or heavy pot over medium heat. Add the diced holy trinity (onion, celery, bell pepper) and minced garlic. Sauté until softened and fragrant, about 5-7 minutes.

Add the sliced andouille sausage to the pot. Cook, stirring occasionally, until sausage is browned and releases its oils, about 5 minutes.

Stir in the soaked and drained red beans, 8 cups chicken stock, 2 bay leaves, 1 tsp dried thyme, 1/2 tsp cayenne, 2 tsp salt, and 1 tsp black pepper. Bring to a boil, then reduce heat to low, cover partially, and simmer gently for 2 hours, stirring every 20-30 minutes. Add a splash of water if it gets too thick.

While beans simmer, cook 3 cups long-grain white rice according to package instructions (usually 1:2 rice to water ratio, simmer 15-20 minutes). Fluff and keep warm.

Once beans are tender and creamy, remove bay leaves. Mash a few beans against the side of the pot with a spoon to thicken the broth further. Simmer uncovered for 10 more minutes to desired consistency. Taste and adjust seasoning.

Serve the red beans over a bed of hot rice, garnished with sliced green onions.