Melt butter in a medium cast-iron Dutch oven over high heat. Add yellow onion, celery, bell pepper, garlic, bay leaf, and cayenne. Add salt, and cook, stirring occasionally, until onions are soft and translucent, about 15 minutes.
Add crawfish and liquid, green onion, and Slap Ya Mama White Pepper Seasoning, and Pepper Sauce, stirring to combine. Cook, uncovered, stirring occasionally, until crawfish tails begin to fry, about 5 minutes. Taste and adjust seasonings if necessary.
Add rice, and stir until combined. If mixture looks dry, add chicken stock. Stir vigorously to release starch from rice, adding more chicken stock, if needed, to maintain moisture level. Add lemon juice and parsley, turn off heat, and stir to combine. Taste and adjust seasonings, if necessary. Stuff this crawfish boudin into chickens or peppers, or batter and fry it into boudin balls.
Recipe by Louisiana Cookin' at https://louisianacookin.com/crawfish-boudin-2/