In a large bowl, combine sugar and egg yolks and set aside. In a medium saucepan, combine heavy cream, milk, honey, mustard seed, and fennel seed. Simmer for 5 minutes. Remove saucepan from heat and stir a few tablespoons very gradually into the egg mixture to temper it. Then stir the egg mixture into the saucepan mixture and return saucepan to heat, stirring constantly. Cook until the mixture coats the back of a spoon. Strain mixture and cool completely. Churn and pour into airtight container to freeze.