For the crema: Whisk together the sour cream, mascarpone, lemon zest, lemon juice, basil and salt. Cover, and refrigerate for at least 1 hour to let the flavors marry.
For the dates: Preheat the oven to 400 degrees F.
Make a small lengthwise slit down the center of each date. Remove the pits and open the dates slightly; make sure they stay intact. Stuff each date with 1 teaspoon of the sausage. Close the dates up and around the sausage¿they won't close completely¿leaving some of the sausage exposed. Wrap each date in a piece of bacon and place on a baking sheet.
Bake for 8 minutes. Flip the dates, and bake until the bacon is crisp, another 8 to 10 minutes. Serve warm, with the crema on the side.