In a small nonstick skillet over medium-high heat, add 2 tablespoons olive oil, and bring to a shimmer. Add the onion and bacon. Season with salt and pepper to taste.
Sauté, stir often, until the onion is caramelized.
Drizzle vino cotto over the onion mixture, add more or less to taste. Reduce heat to low, and simmer for 1 minute, or until the vino cotto begins to bubble. Remove from heat, and set aside.
If using chicken tenderloins, to remove the outer membrane if attached, lift the membrane, and with your other hand, glide a sharp knife under it, gently pressing downward against the chicken with the knife, while pulling the membrane upward, until it is removed. Do this for each tenderloin. Rinse and drain.
In a 12-inch nonstick skillet over medium-high heat, add 2 tablespoons of olive oil, and bring to a shimmer, then add the chicken. Season with salt and pepper to taste.
Turn the chicken often, and cook until golden brown on both sides.
In the meantime, reheat the onion and bacon mixture.
To serve, evenly distribute the chicken onto individual serving plates. Garnish with the onion and bacon mixture. Serve hot. SERVES 4