For the filling, in a small dish mix with cornstarch with just enough of the water to make a slurry, set aside.
In a saucepan combine the sugar, pectin, and the remaining water and bring to a boil. Add the cherries and boil gently for 5 minutes. Pour the mixture through a sieve, reserving the cherries and syrup separately.
Pour the syrup back in to the saucepan and bring back to a gentle boil. Stir the lemon juice into the cornstarch mixture, then slowly pour it all into the syrup while stirring constantly. Continue to stir until completely thickened, about 3 minutes. Remove from heat and add the cherries. Pour into a bowl, then place a piece of parchment paper directly over the surface to prevent a skin from forming as it cools.
Prepare the pastry dough as directed. On a piece of dusted parchment, shape and roll into an 8x10” rectangle. Spread a very thin layer of softened butter over surface of dough (this will give it a puff pastry-like texture). Staring with one of the shorter ends (8”), fold it in thirds like a business letter. Turn dough 90 degrees on counter, then use the rolling pin to roll or ‘pounce’ the dough back into an 8x10 rectangle again. Fold again into thirds as above, wrap in plastic and chill for 30 minutes.
On a piece of dusted parchment paper, roll out the dough to just under ¼” thick. Use a 3-4” round or square cookie cutter and cut out the dough. Because gluten free dough easily cracks when folded, instead of folding the dough over to create the turnovers, 2 pieces of dough will be used then pressed together to create the pocket.
To assemble, mix together the egg wash, and brush it around the outer edge of one of the cut outs. Place 1-2 teaspoons of filling (depending on size of cut outs made) in center, cover with a second piece of dough, then use a fork to press and seal the edges. Lightly brush the entire top of the turnover with the egg wash, then sprinkle with some coarse sugar and some sliced almonds if desired. Repeat with remaining cut outs until all turnovers are formed. With a sharp knife make a small slit in the top of each to allow steam to escape (otherwise turnovers could split open).
Bake at 400°F for 20-25 minutes, or until golden brown.
As an added touch, you can brush the turnovers lightly with a simple syrup once they are removed from the oven, this will produce a nice light glaze.
Simple Syrup – combine equal amounts of water and sugar together in a saucepan and heat until sugar is completely dissolved. Allow to cool completely.