In a large frying pan, heat the oil over moderately low heat. Add the onion and cook, stirring occasionally, until translucent, about 5 minutes. Add the garlic and then the lamb. Cook until the meat is no longer pink, about 3 minutes. Stir in the cumin, tomatoes, and salt. Cover and simmer for 15 minutes.
In a large pot of boiling, salted water, cook the spaghetti until just done, about 15 minutes. Drain the pasta and toss it with the sauce, pepper, and mint.
Variation: Whole-Wheat Spaghetti with Meat Sauce: You can substitute 1 pound of ground beef for the ground lamb. Use the same procedure, but decrease the cumin to 1 1/2 teaspoons and use parsley rather than mint. :
Wine Recommendation: The spiciness of the cumin, the earthiness of the whole-wheat spaghetti, and the gaminess of the lamb are best with a full-bodied, slightly rough red wine such as a Côtes-du-Rhône from the southern part of France.