Wash collard greens thoroughly; remove tough stems. Slice or chop greens, and set aside.

Preheat oven to 350 degrees F. Preheat grill pan or grill to medium-high heat (350 to 400 degrees). Grill pork until well marked on all sides, about 10 minutes.

Transfer pork to a baking dish; oven roast until a meat thermometer inserted into thickest portion of meat registers 155 degrees F, about 15 to 20 minutes. Transfer to a platter; let stand 10 minutes before slicing.

Meanwhile, heat a large, heavy saucepan over medium-high heat; add oil, onions, and garlic and saute 1 minute. When onions just begin to turn golden, add collard greens, by handfuls, stirring until wilted before adding another handful. Stir in raisins; saute until just tender, about 6 minutes. Add a little water, if necessary, for steam. Stir in almonds; season with salt and pepper.

Slice pork and serve on greens.