Combine lime juice, fish sauce, and palm sugar in a small mixing bowl; whisk vigorously until sugar dissolves completely.
Add minced garlic and chopped Thai chili to the lime mixture; stir well to blend.
Toss in the crushed peanuts and mix gently. If using optional ingredients like cilantro, ginger, or lemongrass, add them now.
Taste the dressing and adjust seasoning with additional lime juice for more tang, palm sugar for sweetness, or fish sauce for saltiness.
If using optional oils, add them last and whisk until well incorporated.
Allow the dressing to sit for 5-10 minutes before using to let the flavors meld.
Drizzle over your favorite salad and serve immediately, or store in an airtight container for later use.