In a skillet, heat 1 tablespoon of the oil. Add the sausage and cook over moderately high heat, breaking it up into small pieces, until browned. Add 3 more tablespoons of oil, the garlic and red pepper to the skillet and cook for 1 minute. Add the broccoli rabe and cook, stirring, until tender, 3 minutes. Season with salt. Add the lemon juice and toss. Serve with pecorino.