In saucepan, bring milk, onion, potato, dill, bay leaf and salt to boil; reduce heat and simmer, uncovered, until vegetables are tender, about 15 minutes. Add fish; simmer until fish flakes easily, 5 to 10 minutes. Strain fish mixture, reserving liquid for another use, if desired. Remove bay leaf; let cool.

In food processor, pulse together fish mixture, egg, flour, pepper and generous pinch nutmeg until almost smooth.

In saucepan, pour in enough oil to come 1-1/2 inches (4 cm) up side; heat over medium-high heat until oil thermometer reaches 350°F (180°C), adjusting heat as necessary to maintain temperature. Dip two tablespoons into cold water; without drying spoons, scoop up heaping spoonful of mixture with one spoon and flatten slightly with other spoon. Push into oil. Repeat with remaining batter. Fry, in batches and turning once, until golden, 3 or 4 minutes. Serve with lemon wedges.

Tip: Don't discard the fish poaching liquid; it can be frozen and makes an excellent base for fish soups and chowders.