1. In a blender or food processor, puree the parsley, the smashed garlic, the capers, and the anchovy paste with the olive oil, the wine vinegar, and the salt and pepper.
2. In a large pot of boiling, salted water, cook the penne rigate until just done, about 13 minutes. Drain.
3. In a large bowl, toss the pasta with the parsley mixture, mozzarella, and tomatoes.
Fresh Mozzarella: Fresh mozzarella is a soft, white cheese formed into a ball, which is usually packaged with water in plastic tubs to keep it moist. The cheese has a mild, milky taste that combines well with other, stronger flavors, and melts to a nice oozy texture. It's becoming more and more available in grocery stores; we have seen the Poly-O brand in many locations. Drain the cheese before using.
Test-Kitchen Tip: Cut the mozzarella into cubes first thing and let it sit at room temperature while you prepare the rest of the recipe. That way the mozzarella will melt more quickly.
Wine Recommendation: Look for a white wine that goes well with the saltiness of the capers and anchovy paste and the acidity of the tomatoes. One from the south of France, such as an ugni blanc from the Côtes de Gascogne, will do nicely.