Cook pancetta in a medium saute pan over low heat until crisp, about 20 minutes. Drain on paper towels, then transfer to a large bowl. Pour off fat from pan (a thin film will remain). Increase heat to medium, add shallots to pan, and cook until tender, about 15 minutes.
Increase heat to high; add chanterelles and pine nuts and saute until both are lightly browned, about 5 minutes. Transfer mixture to bowl with pancetta.
In the same pan, warm oil over medium heat, then whisk in lemon juice and vinegar and heat through, scraping up the flavorful browned bits from the bottom of the pan.
Add mixed greens to bowl with pancetta, chanterelles, and shallots. Add the warm vinaigrette and toss salad well. Divide between 4 plates and season to taste with pepper.