Cut peppers lengthwise in half, remove seeds and place peppers cut sides down on baking sheet lined with foil. Broil until charred, about 20 minutes. Cool, remove and discard skins, and cut peppers in wide strips.
Combine peppers, walnuts, garlic, oil and salt in a food processor. Process until chunky.
Combined arugula, ricotta and croutons in a large salad bowl or platter. Place steak on top. Spoon pesto over steak.