Whisk in juice, zest, flour, ricotta and salt until combined.
Heat oil in a heavy skillet over medium to high heat until hot (but not smoking).
Working in groups of 4, spoon 1 tbsp of batter per fritter into oil and fry. Turning it over once, until golden on both sides (takes about 2 minutes). Transfer with a slotted spoon to paper towels to drain and cool slightly.
Dust fritters with confectioners sugar and serve asap.