Add the peanut butter to a bowl, along with the red pepper flakes, lime juice, agave or maple syrup, soy sauce, ginger, garlic, and 1 teaspoon sesame oil. Whisk well to combine. Season to taste with a pinch of salt. Taste, adding more of the sesame oil as desired. Add more lime juice for tang, agave for sweetness, or red pepper flakes for more heat.