Chef Ian Rosenstrauch has a thing for fried chicken. And we should all be grateful for that.

A former line cook at New York City’s Rainbow Room, who then worked for three years as a butcher and gardener at The French Laundry in Yountville, he would go home at the end of his shift and crave fried chicken so much that he’d fry up a batch to eat. Even at 2 a.m. — when he had to be back at work at 7 a.m.

One day, he got the notion to come up with the ultimate fried chicken sandwich. And that was that. He jumped all in, quitting his job a month later, and buying a used food truck that he tricked out, himself, after watching YouTube videos.

He knew he was on to something when he was asked to cater the holiday party for the staff at Michelin-starred Press in St. Helena.

He served the fried chicken sandwich, of course. “They lost their minds!” over it, he recounted proudly. That was no easy feat when you consider that tough crowd included former colleagues of his from The French Laundry.

That’s how Joella’s Deli was born two years ago. He named it after his grandmother, whom he jokes, never cooked anything in her life, but nevertheless whose love had a profound impact on his life.

Although, it has moved around here and there, it now sits parked in an industrial part of Napa, on the property of an automotive shop.

There, the 7-by-14-foot orange cart serves up fried chicken sandwiches so good they’ll make you giddy.

The setting may be all asphalt, but the accoutrements reveal a fine-dining sense of detail. Rosenstrauch actually makes his own sourdough-potato buns for these sandwiches. And everything else that goes on it, from the tangy pickles to the creamy ranch-dressed slaw to the smoky, garlicky hot sauce that dresses the brined, buttermilk-soaked chicken thigh after frying.

After following his Instagram account for ages, I finally was able to time it right for a visit to Joella’s Deli, which is open only Thursday through Saturday, noon to 8 p.m.; and Sunday, from noon to 6 p.m. Although we happily paid our tab, Rosenstrauch, who also follows me on Instagram, offered up a few extra morsels on the house.

There are only two small tables with four chairs total under an awning beside the truck. So, at prime-time, you may have to find a nearby park to enjoy the food or eat in your car. Whatever you do, get plenty of napkins because biting into this sandwich is a messy affair. Thankfully, Joella’s supplies heavy-duty ones.

The chicken sandwich ($18) sports craggy, battered chicken that reminded my husband delightfully of Japanese karaage. It’s juicy throughout and quite crispy, with a slow tickle of heat from chiles in the sauce.

Chicken nuggets ($12) here are a far cry from those at the Golden Arches. This is actual chicken thigh cut into manageable pieces to dip into house-made spicy hot honey and cooling ranch. Rosenstrach calls it a “snack.” I say it’s a true “treat.”

Get them with a side of crispy Cajun fries ($6), crinkle-cut and dusted with cayenne, paprika and other warm spices.

Rosenstrauch often offers specials, too, including that day’s Italian rainbow cookies that are a nod to his New Jersey upbringing. Red, white, and green like the Italian flag, these tender, moist, and intensely nutty tasting slices are made with almond paste. They get coated in a thin layer of chocolate, and layered with lively raspberry-balsamic jam.

It just shows that Joella’s offers far more than just chicken sandwiches. In fact, I can’t wait to go back to try the cheesesteak, the crispy eggplant sandwich, and whatever else Rosenstrach dreams up in the wee hours of the morning.