Combine strawberries, sugar, and vinegar in a small bowl; stir well.
Cover and refrigerate for at least 4 hours, stirring once or twice. (Refrigerating for up to a day is encouraged.)
When it is time to assemble, place ricotta in a medium-sized bowl.
Add powdered sugar and almond extract, and either whisk or stir vigorously.
Place one-fourth of ricotta mixture in the bottom of a lowball glass or individual parfait dish.
Top with 2 heaping tablespoons of strawberry mixture with a little bit of the liquid.
Repeat with another fourth of the ricotta, followed by 2 tablespoons of strawberries and liquid.
Sprinkle with 1 tablespoon pistachios.
Make second serving of parfait following the same steps.
Can be refrigerated for an hour or two or served immediately.