I head out to L&P, in the city's Park Manor neighborhood, to buy a bottle of Bonne Chere. The label lists high-fructose corn syrup, water, distilled vinegar, tomato paste, modified food starch and salt as the top six ingredients. The gallon plastic jug costs $7.50. We taste it in the Tribune test kitchen, alongside mild sauce from Harold's, and it's shocking how close the two are in color, consistency and flavor. But what sticks with me as much as the taste is the store receipt. In the system at L&P, Bonne Chere rings up as "Mild Sauce Original."