Instructions: Make dressing: Preheat oven to 500 degrees and line a baking sheet with foil.

Roast tomatoes on baking sheet in middle of oven 20 minutes. Cool tomatoes and peel. In a blender puree tomatoes and garlic with vinegar until smooth. With motor running, add oil in a stream and blend until emulsified. Season dressing with salt and pepper. Dressing may be made 1 day ahead and chilled, coverd.

Make salad: Preheat grill or grill pan.

Working in batches, cut potatoes into 1/8-inch thick rounds and in a large bowl toss with oil and salt and pepper to taste. Grill potato rounds in batches over moderate heat, turning them occasionally, until tender, about 10 minutes, and transfer them to another large bowl.

Alternatively, roast potatoes in a 450 degree oven: Arrange half of oiled potatoes, lightly overlapping, in 2 large shallow baking pans and roast in upper and lower thirds of oven, turning them occasionally, until golden and tender, about 15 minutes. Roast remaining potatoes in same manner.

Cut ham into 1- by 1/8-inch strips. Chop scallions and celery. In a dry small heavy skillet toast cumin seeds over moderate heat, stirring, until fragrant, about 30 seconds, and cool. In an electric coffee/spice grinder finely grind seeds. To potatoes add cumin, ham, scallions, celery, and remaining salad ingredients.

Add dressing to salad and toss to coat. Chill salad at least 4 hours and up to 1 day.

This recipe yields 6 servings.

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