The chimi reads like a burger but is built like a dressed sandwich, and that is the thing that sets it apart from an American hamburger. The patty is seasoned ground beef worked through with onion, herbs, and warm spice so it carries flavor on its own rather than relying on what is laid over it, then griddled thin and firm. It goes onto pan de agua, a soft, light Dominican water roll with a thin crackly crust, and the rest is a deliberate cool wet system: shredded cabbage rather than lettuce, sliced tomato, pickled red onion, and a pink mayo-and-ketchup sauce poured on with a generous hand. The defining decision is that the dressing is not garnish on a meat sandwich; it is half the build, and the patty is engineered to be its seasoned anchor.
The craft is in moisture management on a roll that wants to give out. The pan de agua is chosen because it is soft enough to compress to the patty and absorbent enough to take the pink sauce, but its thin crust holds just long enough to get the sandwich from the cart to the hand. The cabbage is doing structural work the way lettuce cannot: it is sturdier, it stays crisp under a wet sauce, and its volume keeps the sauce from running straight through the bread. The pickled onion supplies the sharp acid that cuts the rich seasoned beef and the fatty sauce, and the sauce itself binds the loose components into one mass so the sandwich eats as a single thing rather than a stack. This is late-night food assembled fast on a flat-top off the back of a cart, dressed heavily and wrapped to be eaten on a sidewalk, which is exactly why the cabbage and the thin roll are not compromises but the right engineering for the conditions it is sold in.
The variations stay close to the same cart grammar and mostly change the protein and the sauce volume. A chicken or pork version keeps the cabbage, the pickled onion, and the pink sauce intact; a chimi loaded heavier with sauce edges toward something eaten with a fork; the broader griddled-beef family runs from the smashed patty to the regional chains. Each of those is a codified build with its own following and deserves its own article rather than being crowded in here.