To make the vinaigrette, mix together the vinegar, shallot, tarragon, pepper, mustard and salt. Gradually add the oil. Adjust the seasoning to taste.

Slice the goat cheese rounds in half horizontally. Place cut sides down on a baking dish or heatproof skillet. Bake until the cheese is warmed through, but not melted. This will take about 4 minutes.

Toss the endive, greens, grapes, pine nuts and vinaigrette and portion on 4 large salad plates. Carefully lift the disks of warm cheese from the pan and place on top of the salads. Serve immediately.