Rotini con Gamberi, Pomodoro ed Asparagi

1/3 cup olive oil
½ cup white onions, thinly sliced
1 lb asparagus, sliced into 1 inch pieces
1 lb (about 5 medium) fresh plum tomatoes
1 lb medium shrimp, peeled and (unless you're in Spain) de-veined
Salt and pepper
1 box Rotini
2 tbsp fresh parsley, chopped

Cook pasta. Blanch tomatoes (put them in a pot of boiling water for a couple minutes), peel, seed, and chop. Heat oil in a skillet and sautee onions 2-3 min. Add asparagus and sautee another 2 minutes. Add tomatoes, shrimp and simmer 4-5 min or until shrimp is cooked and opaque. Season with salt and pepper. Add pasta and garnish with parsley.