The relish is at its best served shortly after it is prepared.
With the side of a chef's knife, mash garlic with salt. Transfer to a small bowl and whisk in vinegar, sugar and hot sauce. Add papaya, onion and cilantro; toss gently to mix.
Note: Sambal olek, a mix of chiles, brown sugar and salt, can be found in the Asian section of some large supermarkets and at Asian markets.