It's almost always seen with shredded carrot in it.
I use much less vinegar, a little more garlic and instead of chili sauce either chopped up bird chiles or for a similar but less intense spiciness, Serrano chiles. I've also never seen it with peanuts; how weird. A little water's also appropriate.
More specifically:
1/4 cup fresh lime juice
1/4 cup nuoc mam (Thai fish sauce will do)
1/4 water
2 teaspoons rice vinegar (cider vinegar will do)
1 tablespoon sugar
1 mince clove of garlic
1 bird chile or serrano chile, minced (if you use bird chiles, wear gloves)
some shreds of carrot
Keeps for about 3 days before the garlic part starts to taste a little funny; and letting it sit around for a hour or so does help the flavors to mix well.
And adjust proportions to taste; like more "sour", add more lime or vinegar. Too sour, take out the vinegar. Don't like the spiciness? less (or no or less potent) chiles. Wrong amount of sweetness? change the amount of sugar (or maybe the lime if it's sweetness and sourness you want to adjust at once).
Here's one vegetarian version; it lacks the fishiness and is, in fact, totally different tasting, but is a suitable replacement in most ways:
3 tablespoons soy sauce
1 tablespoon rice wine or cooking sherry
1 teaspoon finely chopped garlic
1 teaspoon finely chopped lemongrass
1/8 teaspoon ground cinnamon
1 minced bird chile or serrano chile
1 teaspoon peanut oil
1 teaspoon sugar
1/2 teaspoon salt
Mash garlic and lemongrass into a paste. Mix everything together. adjust to taste.