Bring water to a boil in a saucepan and stir in semolina and salt. Simmer gently, stirring frequently, until semolina is tender and mixture is very thick, 10 to 15 minutes. Stir in milk, butter, and anise seed; simmer until soup reaches desired consistency, 5 to 10 minutes.
Stir milk, butter, and anise seed into soup; simmer until soup reaches desired consistency, 5 to 10 minutes.