Preheat oven to 325 degrees F. Combine boiling water and apricots in a medium bowl. Let stand for 5 minutes. Strain the apricots through a fine mesh sieve, reserving the liquid and gently pressing on the apricots with the back of a large spoon to press out as much liquid as possible. Stir together the drained apricots, the pistachios, 2 tablespoons brown sugar, and the lemon peel in a large bowl. Set aside.

Coat the bottom of a 13x9-inch baking pan with cooking spray. Unroll phyllo dough (keep the phyllo covered with plastic wrap until needed.) Layer 5 or 6 phyllo sheets in the prepared baking pan, lightly coating the tops of the sheets with the cooking spray except for every third sheet which should be brushed with melted butter. Sprinkle with about one-third of the nut mixture. Repeat layering the phyllo sheets and sprinkling with the nut mixture two more times, coating the top of each phyllo sheet with the cooking spray or the melted butter.

Layer the remaining phyllo sheets on top of the filling, coating each sheet with the cooking spray or melted butter. Brush the final sheet with the melted butter. Using a sharp knife, cut the stacked layers into 24 diamond- or rectangular-shaped pieces.

Bake about 45 minutes or until golden brown. Cool slightly in the pan on a wire rack.

Meanwhile, measure the drained apricot soaking liquid. Discard enough of the liquid or add water to the liquid to make 2/3 cup total liquid. Stir together the 2/3 cup apricot soaking liquid, the remaining 2/3 cup brown sugar, and the nutmeg in a small saucepan. Bring to boiling; reduce heat. Simmer, uncovered, for 10 minutes or until reduced to about 1/3 cup. Pour the syrup evenly over the slightly cooled baklava in the pan. Sprinkle the top evenly with coarse kosher salt. Re-cut the diamonds or rectangles to serve.