In a medium sauce pan bring 2 quarts of water to a boil adding a few tablespoons of salt. Quarter the radicchio heads through the stem so that the leaves stay intact. Plunge into the boiling water for 15 to 20 seconds and refresh under cold tap water until cool. Wrap each quarter with bacon and set aside. In a food processor add lemon juice and Dijon. With the food processor running slowly add olive oil emulsifying the vinaigrette. Finish with cumin seeds and season to taste with salt and pepper. Grill the radicchio until bacon is crispy. Top with vinaigrette and serve.