How to Make It
In a medium enameled cast-iron casserole or Dutch oven, heat the canola oil. Add the onion, cover and cook over moderate heat just until softened, about 5 minutes. Uncover and cook over low heat, stirring frequently, until the onion is very soft and caramelized, about 30 minutes longer; add 2 tablespoons of water occasionally as necessary to prevent the onions from scorching.
Add the stock, sherry and leek to the onion. Season with salt and pepper and bring to a boil. Reduce the heat to low and simmer until slightly reduced, about 15 minutes.
Meanwhile, in a large saucepan of boiling, salted water, cook the fregola until al dente, about 15 minutes.
Drain the fregola and add it to the broth along with the thyme and parsley. Simmer until slightly thickened and stew-like, about 5 minutes. Serve the fregola in shallow bowls and garnish with the shaved cheese.