Place the red peppers on a baking pan cut side down. Broil until the skin has blackened.

Place the peppers in a sealable plastic bag for 5 minutes. Remove from the bag. Peel off the skin and discard. Chop the peppers into small strips, and let cool.

Add the arugula and peppers to a serving bowl. Tear the mozzarella up, pat with paper towels to absorb excess moisture. Add to the bowl, together with the sliced basil and black pepper.

Whisk together the oil, vinegar, and anchovy paste, then drizzle it over the salad.

Finish with the chopped green onions, and serve.