What I liked at "Smyrna," a Turkish (!!) resto in Hell's Kitchen, and at Turkish Grill, is crunch, sweet and sour.
But online recipes are full of variations. Fresh tomato alone won't work and you have to hand chop everything superfine. Turns out "ezme" translates to "crush" and is like a salsa but more of a paste. So, based on an amalgamation of recipes below and what I have tasted, the strategy seems to be: mash onions, salt with sumac, de-seed fresh or canned tomatoes, then drain tomatoes of all liquid after chopping - flavor may be best using canned plum tomatoes whole no skin. Plus, tomato paste. Another key: pomegranate syrup or paste. Right! Green and or red pepper has been very subtle, so probably put lemon directly on that before blending. I have had ezme at three different places with a few walnuts and some garlic chopped.
But none of these recipes recreates all this. So until a Turkish chef weighs in, ezme goes down as Turkish secret sauce! Recipes: From a Mediterranean charter tour company, a surprisingly good recipe and explanation. Turkish Cookbook's version. Food.com's take. Some sites call it Acli Ezme. This version from the blog "Saffron and Lemon" is written by a Middle-East food enthusiast in Japan and has some good meat recipes for after lent. I like this site for Turkish cooking tips, but it's not archived well so there isn't an obvious ezme recipe.