Wash and chop the asparagus into one-inch pieces. Toss them with 1 tablespoon of olive oil, salt and pepper, and spread them evenly on a baking sheet.
Dot the asparagus pieces with the butter. Roast at 400 degrees for 15 minutes. Remove from oven and allow to cool.
In the meantime, cook the pasta in salted water. Cool the pasta completely by running under cold water.
Chop the sun dried tomatoes, zest the lemon, and juice it. Chop the green onions, and add all ingredients to a large bowl.
Toss with the remaining olive oil and the butter from the baking sheet. Season accordingly.
Pack into air-tight containers and refrigerate. This pasta salad is much better cold than it is at room temperature. You can try adding freshly grated parmesan cheese as well if you prefer a cheesy version of this dish.