Snap the ends off the wax beans (the part that connects to the stem) and then snap the beans in half again.
Blanch the beans in a large pot of boiling water for 2 minutes, then transfer to a bowl of ice water. When cool, drain.
Chop bacon into small cubes. In large skillet, cook bacon over medium high heat, stirring frequently. When it starts to brown, reduce heat to medium and continue to cook until all the pieces are done, about 20 minutes.
Transfer the cooked bacon pieces to a paper towel covered plate. Drain off excess grease in pan reserving anything that sticks to the pan. Over medium heat, cook the shallots and garlic until tender, about 5 minutes. Add sherry vinegar, stir, and cook for another two minutes. Add cooked bacon, tomatoes and blanched wax beans to the skillet and cook until warm.
Toss in basil, salt and pepper prior to serving.