I used to bemoan the fact that living away from my hometown of Bangkok meant that I couldn't have my favorite snack of firm and crisp fresh Thai guavas with a side of sticky palm sugar-based dip on a daily basis. That is until I've discovered that crisp, tart American apples actually go very well—better, even—with this dip. The dip itself is sweet and salty with a little bit of heat from the fresh chilies. And when combined with the tart apple, both form that sour-salty-sweet flavor combination which people love about Thai food.
In Thailand, you'll find several types of fruit dips. They range from a simple combo of salt, granulated sugar, and dried red chili flakes to something more elaborate like a sticky dip that's made of palm sugar, fish sauce, shallots, dried shrimp flakes, among other things—definitely a bit of a challenge for those who don't see fish sauce and dried shrimp sharing the same plate with fresh fruits.
This dip right here is a good place to start for those who are still apprehensive. It requires fewer ingredients, and does not contain anything that would be considered an "acquired taste." It's also very simple and quick to make.
But there's a catch: you have to use your instinct.
Palm sugar is one of those natural, barely-processed ingredients that can be somewhat tricky. The level of sweetness seems to vary from brand to brand and batch to batch. Not drastically but quite noticeably. This means you should use the recipe as a guide and adjust the amounts of salt and palm sugar to taste. You also need to adjust the amount of water according to how much moisture is in your palm sugar too.
For example, palm sugar in Thailand (and perhaps Southeast Asia in general) has much more moisture than palm sugar that's generally sold in the US (even though it comes from Thailand—weird, I know). This means that if you use palm sugar from Thailand, you may want to omit the water which the recipes calls for altogether. You can always add more if the dip ends up being too thick.
As long as you end up with a cooled dip that has the consistency of honey, you're good. As for the taste, it should be primarily sweet and secondarily salty. This is not one of those recipe where you add a tiny, tiny amount of salt just to round out the flavor or bring out the sweetness in the dish; this dip should be almost as salty as it is sweet. Think sea salt caramel that's a little saltier than usual.
Chilies? That's kind of optional, actually. I like chilies in this dip mostly because that's the way it's made traditionally. But if heat is not your thing, feel free to leave them out.