This is a very easy brew, and a pleasure to make a beverage completely from raw ingredients. I'm not a fanatic about the health benefits of using natural ingredients nor am I at all concerned about knowing exactly what's in my food. I know some people are, so I won't bash those two schools of thought. I just really enjoy making things completely from scratch.
For the syrup:
1 cup brown sugar
1 1/2 cup white sugar
juice and zest from 1 lemon
ginger root roughly the size of your thumb.
2 cups water
Grate the ginger root and lemon zest into a saucepan in 1 cup of water. Simmer covered for 20 minutes and allow to steep while cooling for another 20 minutes. Strain this mixture to remove the pulp, then filter through a coffee filter. Replace the pulp in the sauce pan and repeat with the second cup of water. This is not extremely necessary, but I feel like I get the most flavor out of the mash this way. I could be crazy, though.
Add your ~2 cups of filtered liquid to the white and brown sugar in a clean saucepan. Bring this to a simmer to dissolve the sugar and add the lemon juice.
This amount of syrup is meant for 3 gallons of beverage, so add carbonated water accordingly.
Ginger Beer vs. Ginger Ale
While most are familiar with ginger ale, there conflicting opinions on what exactly ginger beer is. Jamaican style ginger beer is a soft drink similar to ginger ale, but very spicy with some strong ginger. English ginger beer is an alcoholic drink home brewed from a ginger beer plant, which is a combination of certain strains of yeast and bacteria, skimmed off from the drink and saved for subsequent batches. There's a company in the UK that will sell you a portion of ginger beer plant if that's what you want to do.
This recipe, as presented, is spicier, with more citrus notes and less sweet than a typical ginger ale, but milder than a Jamaican ginger beer. In my opinion, this is easily adjusted by the amount of ginger you add, less for ginger ale, and more for ginger beer.