The most obvious and common dining ritual that everyone just takes for granted is in the opening of a bottle of wine. The server presents the bottle, whips out their key, cuts the foil, and pulls out the cork. The server may or may not present the cork to the diner to be sniffed. The server then pours a bit of wine and allows the diner to check it. The diner almost invariably nods, and then the server pours the full portion.
Most people don’t understand the purpose of all this. It’s not for the diner to verify that they “like” the wine. It’s to check whether the wine has become corked. You don’t need to taste the little splash in your glass to verify this, either; a quick sniff is enough because the odor is strong and distinctive. Personally, I don’t bother to taste; I just smell and (presumably) nod. Sometimes the server is confused when I do this, but at the top-end places, especially when I’m being served by a qualified sommelier, I occasionally see a small smile of recognition. Most people don’t know the basis for the sample pour, so they treat it as a “do you like the wine?” test, which is wrong.
Modern production, distribution, and cellar management practices in the wine industry has made corking an increasingly rare problem. In thirty years of fine dining, I’ve never been presented a corked bottle. Nevertheless, the practice persists, and everybody goes through the motions because it’s part of the experience. Pretty much the definition of a ritual.
For another category of ritual, you could consider dishes that are prepared tableside. For example, if you’ve ever been to a high-end steakhouse, you might have seen an offer for Caesar salad to be made this way. The server pushes a wheeled cart to your table, bearing all the ingredients and equipment needed to assemble the salad. Usually, they make the dressing first, directly in the serving bowl, often incorporating various theatrical flourishes. Then they bring in the body of the salad, swirling and tossing to distribute the dressing over the greens. It doesn’t really improve the flavor or anything, but the fact that it’s prepared in front of you fools your brain into perceiving it as “fresher” and therefore better. You can see a sample video of one restaurant’s presentation here.
Another highly ritualistic tableside preparation is Canard à la presse (pressed duck), sometimes called Canard au sang (literally, duck with blood). In this dish, a whole duck is roasted until done to rare. The duck is then carved, removing the thighs and breasts. The thighs are set aside to be served in the following course. The carcass that remains is placed in a special device with a screw-down center, which slowly compresses the duck’s body to squeeze out the fluids — not just the blood, but also pulverizing the bones to extract the marrow. This liquid is added back into the wine-based sauce over which the duck was originally roasted, and the breast is sliced very thin and presented in this combined sauce.
The reason it’s a ritual is that all of this is done at your table, or at least in the dining room in view of the diner. You can watch a sample video here. This whole process could be done in the kitchen and the finished plate simply brought out and served, but the tradition of the dish — the ritual — is that the process is laboriously performed for the enjoyment of the person who ordered it.