For dressing: In a small bowl, stir together salad dressing and cayenne pepper. Set aside.

For sorrel mixture, in a large bowl, combine sorrel, desired meat, artichoke hearts, and olives. Toss lightly to mix. Cover; chill in the refrigerator while preparing crust.

For a 14-inch round pizza, on a lightly floured surface place 1 sheet of pastry on top of the other sheet, staggering corners. Roll pastry from center to edge, forming a 14-inch circle. (For a 15 x 10-inch rectangular pizza, place pastry sheets on top of each other without staggering the corners. Roll out pastry, forming a 15x10-inch rectangle.) Wrap pastry around the rolling pin. Unroll pastry into a 14-inch deep-dish pizza pan (or a 15 x10 x1-inch baking pan). Prick bottom well with the tines of a fork. Bake in a 375 degree F oven for 25 to 30 minutes or until pastry is golden brown. (Pastry may shrink).

In a medium mixing bowl, combine fontina and Muenster cheese. Sprinkle 1-1/2 cups of the cheese mixture over the warm crust. Top with mushrooms. Return crust to the oven. Bake for 4 to 5 minutes more or until cheese begins to melt.

Meanwhile, pour dressing over sorrel mixture and toss lightly to coat. Spread sorrel mixture over melted cheese on crust. Sprinkle with remaining cheese mixture. Return to oven. Bake for 4 to 5 minutes more or until cheese is melted.

To serve, immediately garnish with tomato slices. Cut into wedges or squares. Makes 8 main-dish servings.