Combine the onions, bell peppers and celery and set aside. In a heavy saucepan, heat the oil over medium-low heat. With a whisk, whisk in the flour a little at at a time until smooth. Continue cooking, whisking constantly, until roux is light brown. 

Remove from heat and with a spoon immediately stir in the vegetable mixture, cayenne and black and white pepper. Return pan to high heat and cook about 5 minutes, stirring constantly. Add the bay leaves, jalapeño and garlic, stirring constantly. 

Continue cooking for another two minutes. gradually incorporate the stock to the roux, stirring constantly, approximately 1/2 cup at a time. Bring final mixture to a boil, then reduce heat to a simmer and cook until the sauce reduces to approximately 3.5 cups, about 15 minutes.