Pasta and Lentils: Pasta e Lenticchie

Name: Pasta and Lentils: Pasta e Lenticchie
Ingredients: 1 1/2 cups dried green or brown lentils, preferably Castelluccio variety, washed and soaked for several hours; 1 small stalk celery, halved; 2 tablespoons extra virgin olive oil, plus extra for garnish; 1 slice pancetta or bacon, finely chopped; 1 onion, finely chopped; 2 cloves garlic, finely chopped; Pinch red chile flakes; 2 tomatoes, peeled and chopped; Salt, to taste; 7 ounces tubetti or spaghetti, broken into short pieces; 1 tablespoon chopped fresh parsley