In a large, deep skillet, heat the oil. Add the onion, pancetta, anchovy and sliced garlic and cook over moderately high heat, stirring, until the onion and garlic are softened, 8 minutes. Add the tomato paste and stir for 1 minute. Stir in the chicken livers. Add the vinegar and cook until nearly evaporated. Add the vermouth and cook until nearly evaporated and the livers are just pink within, about 3 minutes. Scrape the mixture into a food processor; let cool slightly.