In a food processor or blender, add garlic and ginger and pulse until coarsely chopped. Add cilantro, mint, jalapeño, lime juice, water, and sugar and pureé until smooth.
Season to taste with salt (I like 1/2 teaspoon). Adjust consistency with additional water if desired.
Notes
Ginger: To peel the ginger easily, rub the brown skin with the tip of a spoon. Or, substitute 1 tablespoon of fresh ginger paste (such as from Gourmet Garden).
Jalapeños: The seeds and membrane hold the spiciest part of a jalapeño (although overall spiciness varies from pepper to pepper). For a less spicy sauce, omit the seeds and white inner membrane.
Yield: This recipe makes 3/4 cup sauce (12 tablespoons total).
Storage: Store leftovers covered in the refrigerator for up to 4 days.
Freezer: The sauce can be frozen for up to 3 months. Thaw overnight in the refrigerator.