Place the pistachios and 2/3 cup sugar in a blender or food processor. Pulse until the pistachios are a fine powder. Add 1/2 cup milk and pulse until the mixture is thick and smooth like a paste. Set aside.
Place the heavy cream and 1 1/4 cups milk into a medium saucepot over medium heat and bring to a bare simmer. Whisk together the cornstarch, salt, remaining cup milk and remaining 1/2 cup sugar together in a medium bowl to form a slurry. Pour the slurry into the saucepot and cook, stirring often, until the mixture becomes thickened and lightly coats the back of a spoon, 5 to 7 minutes.
Whisk the egg yolk in another medium bowl until it is thick and light in color, about 1 minute. Slowly whisk 1 cup of the milk mixture into the yolk to temper it. Pour the rest of the milk mixture into the bowl and whisk to combine. Whisk in the almond extract, orange juice and all of the pistachio paste until smooth. Strain into a loaf pan, then cover with aluminum foil and place in the freezer.
Stir the gelato with a fork every 2 hours to break up the ice crystals until the gelato is fully set, about 8 hours. Once the gelato has set, place a piece of plastic wrap on its surface, then wrap the whole loaf pan tightly to prevent ice crystals.
Serve with a sprinkling of chopped pistachios and sliced strawberries.