Note: Seedless grapes are a big labor-saver; they let you skip the whole business of first "slipping off the skins" and then straining out the seeds. "Slipping off the skins" isn't as easy as it sounds and can be downright time-consuming.
Wash the grapes and blot them dry. If they are seedless, simply cut each in half. If they have seeds, "slip off" the skins (or, if necessary, peel the skins); set the skins aside.
Put the halved seedless grapes (or the peeled grapes with seeds) into a small saucepan. Cook over medium-high heat, stirring and breaking up grapes with a wooden spoon, until the mixture comes to a boil. Reduce the heat to low and simmer 5 minutes, stirring.
For grapes with seeds: Put a sieve over a bowl and press the grape pulp through it, straining out the seeds. If the pulp doesn't go through the sieve, pick out the seeds from the pulp in the sieve, discard them and add the de-seeded pulp to the juice in the bowl.
For all grapes: In a medium bowl, stir together the 1 cup of sugar, the ¼ cup of flour and salt until well blended. Stir in the grape juice and pulp, the skins if they had been removed, the lemon juice and the melted butter.
Preheat the oven to 400 degrees. Line a 9-inch pie plate with the crust, crimp the edge and pour in the grape mixture.
Prepare the topping: In a medium bowl combine the ½ cup of flour and the ¼ cup of sugar. Using a pastry cutter or two knives held next to each other, cut the butter into the dough until the mixture is in crumbs. Sprinkle evenly over the fruit filling.
Bake for 40 minutes, covering the edges of the crust with foil if they begin to darken too much. Cool on a rack and refrigerate if desired.
Nutrition information per serving:
Carbohydrates 63 g
Protein 3 g
Fat 14 g
including sat. fat 6 g
Cholesterol 21 mg
Sodium 230 mg
Calcium 16 mg
Dietary fiber 1 g
Diabetic exchanges per serving: 1 fruit exch., 1 bread/ starch exch., 2 other carb. exch., and 3 fat exch.