Put the ginger, garlic, peanut butter, soy sauce, lemon juice, and Sriracha into your blender or food processor. Blend until smooth, adding water by the tablespoon as needed to get things moving.
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Notes
How much water you use depends on how thick you want your sauce, the peanut butter you chose, and what sort of blender you're using. A high speed blender won't need as much liquid to get things going. For a thinner sauce (like a salad dressing), use more water. For thicker, back off on the water.Leftover sauce will keep for 3-4 days in the fridge.