Gluten-Free Orzo and Bean Soup with Pequin Chile Oil

1. Soak the beans overnight in cold water. Drain them and put them into a large, heavy pot. Add 1⁄2 cup olive oil, the peeled intact onion half, the celery stalk, bay leaf, and 10 cups cold water. Bring to a boil over high heat, then reduce heat to medium-low and simmer, stirring occasionally, until beans are very tender, about 2 1⁄2 hours. Season with salt to taste. Remove and discard the onion, bay leaf, and celery.
2. In a heavy, 5-quart saucepan, heat the remaining 1⁄2 cup olive oil over medium-high heat. Add the minced onion, minced celery, and carrot, stirring briefly. Let the vegetables sizzle for a moment in the oil, then lower the heat to medium-low or low and cook, stirring occasionally, until the vegetables have softened and are slightly translucent, about 10 minutes. Add the garlic, rosemary, and red pepper flakes to the pot, stir well, and let cook for a minute or so. Stir in the tomato paste, then add the beans and the bean cooking liquid to the pot. Bring to a boil over high heat, stirring occasionally, and then lower the heat and simmer for about 10 minutes.
3. Remove 2 cups of beans from the pot and puree them with 1 1⁄2 cups water in a blender until smooth. Stir the pureed beans back into the pot and return to a boil. Stir the pasta into the pot and lower the heat to simmer, stirring often. Cook until the pasta is tender yet still retains a slight firmness in the center, about 20 minutes. Stir in the fennel and 1⁄2 cup cold water. Season generously, to taste, with salt and let rest 5 minutes before serving.
4. Drizzle with Pequin Chile Oil or an extremely good, grassy extra-virgin olive oil, and serve.

PEQUIN CHILE OIL

1. In a small saucepan, heat 1⁄2 cup of olive oil over medium-low heat until hot to the touch, about 3 to 4 minutes. Remove pot from the heat. Stir in 2 tablespoons of pequin chile flakes or other hot red pepper flakes and let them steep for at least 30 minutes. Cool the chile oil, and then transfer it to a covered container. Stir well before using to ensure chile flakes are suspended in each spoonful of oil. You can store the oil, refrigerated, for up to 1 month.