In a mixing bowl, combine flour, sugar, and salt until evenly mixed
Add cold butter and rub into the flour until crumbly
Mix in egg, vinegar, and water to form a smooth dough
Knead lightly, then cover and let rest for 30 minutes
Roll the dough thin (about 1–2 mm thick) on a floured surface
Cut into circles (about 4–5 inches wide)
Wrap each circle around cannoli tubes, sealing edges with water
Heat oil in a deep pan to 350°F (175°C)
Fry shells until golden and crisp, about 2–3 minutes
Remove carefully and let cool before sliding off molds
In a bowl, mix ricotta, powdered sugar, and vanilla until smooth
Fold in chocolate chips
Pipe filling into both ends of each shell just before serving