Combine the agave and water in a small saucepan, and whisk until uniform.
Add the garlic and ginger, and bring to a boil. Reduce the heat to a modest simmer, and let it cook, uncovered, for about 5 minutes, or until reduced by about ⅓ (imprecise).
Add the soy sauce and let it bubble over low heat for another 5 minutes.
Remove from the heat, stir in the lemon juice, and let it cool and infuse for at least 30 minutes before fishing out the garlic and ginger.
Store in a covered little container at room temperature, and serve as desired.