Bring a large pot of water to a boil.
In a small pot, steep the saffron in the stock over medium heat while you make the ragu.
In a medium Dutch oven or large skillet, heat the EVOO, two turns of the pan, over medium-high. Add the lamb and cook, breaking up with a spoon, until browned, about 5 minutes; season with salt and pepper. Add the garlic, shallots, rosemary and citrus peels; stir for 2 to 3 minutes. Add the tomato paste and stir 1 minute. Add the wine and simmer until the mixture is reduced by half, about 5 minutes. Add the saffron stock and reduce the heat to medium. Let the sauce simmer, stirring often, until thickened, about 20 minutes. Meanwhile, salt the boiling water, add the pasta and cook until al dente.
On a cutting board, chop together the orange zest, lemon zest, mint and parsley.
Drain the pasta, reserving 1/2 cup of the pasta cooking water. Stir the cooking water into the sauce. Remove the rosemary sprig and peels from the sauce. Top the pasta with the sauce and sprinkle with the citrus-herb mixture.