We ate this amazing thing in Thailand many years ago. Is it a dip? A sauce? Not sure but we're happy to eat it with some sticky (glutinous rice).
Grill eggplants and hot green peppers. This is best done over a fire but you could also do it in your oven. The skins should char and blister. Put them in a dish and cover with a cloth to sweat them a bit. This makes it easier to peel the skins off. Peel the skins off! In a mortar and pestle, smash up some garlic then add the green pepper and smash some more then add the eggplant. You want a nice chunky mess. If you don't have a mortar and pestle that's big enough, you can roughly chop the veg (mince the garlic). Season with fish sauce and lime or lemon juice. It should be smoky, fishy, spicy and tangy. Serve with sticky rice and some grilled meat or boiled eggs.