Rinse corned beef and place in a large saucepan with sugar, vinegar, cloves and bay leaves. Add enough water to cover.
Bring to boil on high. Reduce heat to low and gently simmer, covered, for 1-1 ½ hours, until a skewer inserted is easily removed. Remove pan from heat and set aside to cool in liquid.
Meanwhile, make parsley sauce. Melt butter in a saucepan on medium heat. Cook onion for 2 minutes, until soft but not brown. Add flour and cook for 2 minutes, stirring. Gradually stir through milk. Bring to boil, stirring constantly, until sauce thickens slightly. Season to taste and stir through parsley.
Slice corned beef and serve with parsley sauce and steamed vegetables.