In a food processor, process sun-dried tomatoes, walnuts, basil, yeast flakes, garlic, and sea salt until smooth. Add reserved water, 2 tablespoon at a time and pulse until pesto is smooth. In a large bowl, combine pasta, asparagus and sun-dried tomato pesto, stir to combine. Garnish with fresh basil leaves and serve as a side dish or with a salad.