Combine the sugar and 4 tablespoons of the water in a heavy saucepan that can hold at least 2 quarts of liquid. Bring the mixture to a boil. As soon as it turns a light golden color take the pan off the heat. According to Gene the caramelization happens in a flash and you have to keep an eagle eye on the proceedings when you reach this stage. While beating it with a whisk, slowly pour in the balsamic vinegar. Keep your face and body as far from the pot as possible in case the caramel splatters. If little sugar balls appear in the syrup it indicates that some of the sugar has crystallized. Put the pan back on the heat and stir until the sugar balls dissolve, remove any that don't.
With the pan off the heat, and while whisking constantly, slowly add the olive oil in a thin stream, about pencil-width thick. Next, whisk in the remaining 2 Tablespoons of water. Then add the garlic, salt, and pepper.
The dressing should be fully emulsified by this point. It is ready to use now, but if you need to store it; chill it in a covered container, then heat it slowly in a pan over low heat until it thins. Refrigerated, this dressing will keep for at least two weeks.
Pick over the lentils carefully to remove any rocks or foreign objects first. Place lentils and water in a saucepan, bring to a boil, then reduce heat and simmer, uncovered, for about 20 minutes. Stir and check occasionally. Add more water if necessary. When the lentils are tender but slightly chewy add the currants and simmer 2 minutes longer.
Drain the lentil-currant mixture well and put into a bowl. While the mixture is still hot add the Caramelized Balsamic Vinaigrette and stir in well.
Add the tomato pieces, shallots, walnuts, salt and pepper. Stir in well. You can serve it warm or chill it first. Sprinkle on the chopped basil leaves just before serving.
Gene also likes to add finely-chopped celery to this salad for extra crunchiness.