Place lemongrass, shallot, ginger, garlic, and cayenne into the bowl of your food processor. Pulse until finely chopped.
Heat ½ teaspoon oil in a saute pan and add vegetable puree to the hot oil. Sauté until fragrant over medium heat, 2-3 minutes.
Place the peanuts in the bowl of your food processor and process until finely chopped. Add the peanuts to the onion mixture in the pan and sauté until lightly toasted, 1-2 minutes.
Add the water, soy sauce, and brown sugar. Mix well. Bring the mixture to a simmer and simmer over medium heat until thickened to your desired consistency, 3-5 minutes.
Serve warm or refrigerated until needed and serve chilled or at room temperature.
Notes
While the calorie count here may look high, check the serving size on your favorite jarred peanut sauce. Typically, the serving size ranges from 2 teaspoon to 2 Tbsp. We're giving you a ¼ c serving, because you'll want to eat this sauce with a spoon. Trust us.