In a large non-stick pan, sauté pancetta, stirring frequently, over medium heat, until crisp and lightly golden.
Add 1 tablespoon of butter to pan. Add asparagus pieces and leek and sauté until asparagus is tender crisp, about 5-6 minutes.
Add garlic, lemon and orange zest, toasted pine nuts and parsley and sauté for about 1 minute, until fragrant.
Season to taste with freshly ground pepper and salt and serve immediately.