The first time I tasted dukkah (also spelled duqqa and dukka) - at a spice shop in Jerusalem - I liked it so much that I bought a large bag of it for myself and my foodie friends.
Back in Hong Kong, I tried to reverse-engineer the recipe. I was able to figure out that the blend contained pistachios, toasted coconut, dried garlic slices, sesame seeds, salt and dried spices, but the mixture I created just didn't taste right. So I searched online and found there isn't one definitive recipe. All the recipes contained salt, dried spices (but they varied) and nuts, not necessarily pistachios; many called for sesame seeds and some had dried chillis and/or garlic and/or herbs.
The advantage of mixing your own dukkah is that you can change it according to what's "right" for you. If you like hazelnuts or almonds more than pistachios, use those; if you dislike heat, omit the chilli. Mixing your own also lets you tweak the recipe for the occasion: add some dried mint leaves if you're serving your dukkah with lamb; mix in some lemon zest if it's an accompaniment to fish. It's important that all the ingredients are dry, because part of the pleasure of dukkah is the crunch, and moisture will make it soggy - toast the sesame seeds and whatever nuts you're using, and if you're adding garlic, fry it until crisp, then drain it thoroughly on paper towels.
The spice vendor in Jerusalem had me taste the dukkah with a small bowl of pilaf, which was delicious. Sprinkle it at the last minute (so it stays crunchy) over salads and grilled meats and seafood, or serve a bowl of it with some olive oil, to use as a dip for bread.