I’m not talking about a fancy restaurant or who you’re eating with, but location, location, location! 
My #1 is eating rice balls with dried seaweed at the beach. It was always cold and sometimes later in the day turning a bit hard and sour, but there’s nothing greater than breathing in the salt air, making the rice taste a bit saltier and the seaweed like it just came out of the ocean.
Next would be eating Okinawan donuts at grandma’s kitchen table. I never saw her making them and rarely ate them fresh (for the longest time I thought they were supposed to be oily and slightly stale), but she would almost always have a bowl of them on the kitchen table. She barely spoke English, so we didn’t say much to each other, but I’d sit there and watch her putter about the kitchen (where she always seemed to be) and eat my fill. She’d always tell me to take a few with me, but I rarely did as it was never as special eating them at home.
The following are in no particular order.
Eating Okinawan pig’s feet soup at Grandma’s. It was always a special invite when my Dad would say “We’re going up the house.” to eat pig’s feet soup. Usually my grandparents had already eaten, but the long table (a piece of plywood) would be set up and the six of us, later just my parents and me as my siblings were in their late teens would eat together.
My Grandma would put pieces of short cut spareribs in the soup, but thinking back on it, I think sometimes the ‘spareribs’ were sometimes tiny pig’s feet, but I’d happily eat them with my parent’s assurance they were spareribs. We always ate it there, never bringing home any extra, partly because my Mom didn’t like it (her parents were from mainland Japan) and oddly, my Dad did, despite his not liking pork because he had so much of it as a child (traditionally, Okinawan’s rarely eat beef).
Hamburgers at the carnival. Flat, slightly peppery and far from the best burger, but something about eating it at the carnival was a must. I’d eat it while walking around the usually slightly muddy ground and it was even better at the Farm Fair when the flavor of the burger was enhanced by the smell of the animals!
Dobash cake at the beach park. This one is largely because my platonic female friend bought it for me for my birthday as a surprise. I’ve never had cake at the beach before or since and probably never will to preserve the memory of that day. Like the rice balls, smelling the salt air while eating the cake, now warm was something special.