In a glass or ceramic bowl, combine the vinegar and the water. Remove the outer leaves from each artichoke and trim the tops and bottoms. Lay the artichoke on its side and, with a small sharp knife cut away from the bottom towards the top on a slant, to form points. The edges should look scalloped, the bottoms rounded, and the tops pointed. As you trim each artichoke, place it in the bowl of acidulated water to stop it from discoloring.

In a large nonmetal saucepan, heat the olive oil over medium low heat. Add the bacon and cook for about 10 minutes, stirring occasionally, until golden. Pour off all but about 1 1/2 tablespoons of fat from the pan and discard it. Add the onion and cook for 6 to 7 minutes more, until softened, then add the garlic and cook for 2 minutes more, until the aroma of the garlic is released. Add the tomatoes to the pan and increase the heat to medium. Cook for 10 to 15 minutes, until all the liquid has evaporated. Add the broth, salt, and pepper and bring the liquid to a boil. Drain the artichokes well and add them to the pan. Reduce the heat so that the liquid is simmering and cook for about 25 to 30 minutes, covered. Transfer the artichokes to a serving dish and keep warm in a low oven. Increase the heat to high and boil the sauce until it has reduced to about 1 cup. Taste for seasoning and then pour the sauce over the artichokes. Squeeze some lemon juice evenly over the artichokes, scatter the toasted pine nuts over the top, and serve.

Note: To toast pine nuts, preheat the oven to 350 degrees. Spread the nuts on a cookie sheet and toast in the oven until golden, about 10 minutes. Set aside to cool.