Preparation
1. In a large nonreactive (nonstick) saucepan, combine maple syrup, corn syrup, water, sugar, fresh ginger, ground ginger, and salt.
2. Bring to a simmer, allowing it to simmer for 2 to 3 minutes.
3. Remove from the heat and let it cool for 10 minutes.
4. Strain the sauce through a fine mesh strainer, pressing on the ginger to remove as much flavor as possible. Discard ginger.
5. Stir in walnuts, vanilla, and lemon juice, mixing to combine.
6. Allow the sauce to cool a little more before serving over ice cream.
7. It can be stored in the refrigerator and reheated in the microwave in 10-second intervals. It can be stored for up to a month.