“I wasn’t a very religious person when I got into this business,” Eric Christensen said. “But I’ve become one over the years, because mother nature throws so many things at you.”

The business in question is the citrus industry, where Mr. Christensen holds a specialized niche. He and his wife, Kim, run Rising C Ranches, a small California operation that’s become a leading purveyor of hard-to-find citrus fruits – some of them heirloom varieties, others just rare to the American market, but all of them bursting with an unusual depth and intensity of flavor.

“For centuries, fruit was the dessert in many cultures,” he said. “It was the special treat. I’m not trying to relive the past, but I want to make sure people can still appreciate this food for the special thing that it is.”

If Mr. Christensen sounds like a bit of a citrus evangelist, at least he practices what he preaches. He employs sustainable farming methods, eschewing pesticides in favor of natural predators whenever possible. His conversation is peppered with references to soil quality and sugar-to-acid ratios. And he’s absolutely obsessed with freshness.

“We pick and pack to order,” he explained. “So when we ship a box of fruit, it was on the tree just a day or two earlier. The big commercial growers pick and then sell off from that inventory, so the fruit you get at the supermarket may have been in cold storage for weeks. And once you taste the difference, it’s obvious.”

It’s true. Mr. Christensen’s heirloom navels are a quantum leap beyond Sunkist, and his fortunas (a type of mandarin) have an intense tartness that’s sharp but oddly addictive, like sour candy. He also offers lots of unusual varieties with no mass-market counterparts – limequats, variegated pink lemons, sweet limes, and the bizarre multi-fingered citron known as the buddha’s hand. Comparing Rising C’s citrus to mainstream fruit is like comparing, well, apples to oranges.

Rising C got its start in 1988. Mr. Christensen had worked for 20 years as a grower’s representative in the commercial fruit packing industry, serving as the link between farmers and packing houses, when an older grower offered him a sweetheart deal on a small farm.

“I’d learned a lot from those farmers and developed a love for specialized, different varieties, and that’s what I had in mind,” he explained. But as with so many success stories, this one hinged on a lucky break.

“Our neighbor was an old Mexican-American gentleman who had a sweet lime tree in his yard,” Mr. Christensen recalled. “So we grew some of them too, planning to sell them to the Hispanic market. The second year we were growing them, we got a knock on the door from this Middle Eastern fellow, and he wanted to buy the whole crop.”

The buyer, it turned out, was Iranian. Mr. Christensen had known there was a large Iranian population in California – a lot of them moved there when the shah was deposed in 1979 – but hadn’t known they liked sweet limes, which have very low acidity and an extremely mild flavor. “That’s when I realized there were so many ethnic markets available, which just made me more determined to find specialized fruits to sell to them.”

There was another lesson from this experience: Mr. Christensen began to learn that many of his new customers would pay a premium price for fruit with the green stem and leaf still attached, which has become Rising C’s visual trademark. “The Chinese and the Middle Easterners really like it, and even demand it,” he said. “It’s a great barometer of freshness, and they’re used to seeing it that way in their home country, where refrigeration isn’t necessarily the norm and buying daily at the market is a ritual.”

It looks great, too. It may seem like a small thing, but think of the difference between loose tomatoes and ones that are sold on the vine – that extra bit of green makes a huge visual difference. It makes such a big difference, in fact, that Rising C does a big business selling stem-and-leaf fruit to restaurants just for display purposes.

But you don’t have to be a restaurateur to sample Rising C’s fruit. It’s available for mail-order atripetoyou.com. Prices for the fruit itself are about $2 a pound (although the shipping charges can ultimately double or even triple that base price). The selection varies from week to week; a good bet is to go with the “Farmer’s Choice” option, which consists of a 20-pound assortment of whatever’s fresh that day for $42 plus shipping. Here’s some of what you might expect to receive, along with Mr. Christensen’s descriptions of them:

HEIRLOOM NAVEL “This is the old-line navel that made California so famous, that built those mansions in San Bernadino, and transformed this agricultural economy. It fell out of favor in the late 1950s, as higher yield varieties were developed. But the flavor of these older varieties are much more robust, more intense. And the soluble solids, which means the sugars, are proven to be higher.”

GOLD NUGGET “A new mandarin variety, developed by the University of California a few years ago. It’s seedless, pale-skinned. Not the greatest-looking piece of fruit, but it’s got great flavor and it’s more fleshy, less watery, than most mandarins.”

TAROCCO BLOOD ORANGE “A pigmented fruit that has a very sublime flavor, with hints of raspberry or strawberry. We don’t grow these ourselves – they’re grown by a radiologist in Minnesota, who happens to have an orange grove here in California, just up the road. He went to southern Italy, where the tarocco is very popular, and drank the tarocco juice there every morning. He came home and couldn’t wait to grow his own, and we get them from him.”

MINEOLA “A cross between a grapefruit and tangerine. This is the ideal time for it, because in April the acidity level in the mineola has dropped. That lets the flavor come through much more clearly. It’s a wonderful piece of fruit.”

Granted, Mr. Christensen’s a little biased. But I’m not, and I can vouch for the excellence of Rising C’s product. The only downside is that you might not be able to settle for supermarket fruit ever again.