One of the happiest combinations (IMO) is that of mango and habanero chiles. Try this:
1 T peanut oil (vegetable oil is fine)
½ c diced onion (avoid any SUPERsweets)
1 habanero pepper, diced (seeds and ribs optional; you can use Scotch bonnet, or whatever other chile you like, but habanero makes for a glorious match)
2 t garlic, mashed to a pulp
1½ c diced dried mango
¼ c fresh lime juice
½ c rice vinegar (plain white vinegar will do if you absolutely must)
2 T light brown sugar
½ t grated ginger
½ t coarse salt (I like sea salt, but Kosher's fine)
¼ c fresh cilantro leaves (opt)
Place a saucepan over medium-high heat and add oil to the pan. Once the oil shimmers, add the onion and habanero and cook until the onions are translucent (figure 3 to 4 minutes). Add the garlic to the pan and cook for 30 seconds. Deglaze the pan with the lime juice and vinegar, add diced dried mango and then reduce the heat to low.
Add sugar, ginger, and salt to the pan. Continue to cook the sauce until mangoes go very soft, about 5 minutes. Remove the pan from the heat and allow the sauce to cool (not go stone-cold, though) then puree in a blender, adding cilantro if desired.
This is excellent on seafood, and on anything with a Caribbean or "Nuevo Latino" thing going on. You can also add, say, the grated zest of the lime, or cracked white pepper, etc. Play w. it.
-Joe