My friends Glenn and Amy Shinsato have impeccable taste buds and bold culinary creativity. Using both, they recently hit upon a most delicious creation: smoked shoyu.

They gave me a bottle to try, and it was amazing: As expected, the smokiness of apple wood chips provided a complexity to the salty umami of the shoyu, but that was just the beginning. Their finished product was so much more, with a balanced, rounded, nuanced flavor.

Glenn Shinsato said they added dimension by steeping other items in the shoyu, hitting all the right notes — vanilla for an “impression of sweetness,” konbu (dried seaweed) for some natural MSG, a touch of awamori (Okinawan liquor) for depth, and hojicha (roasted Japanese green tea) for floral aromatics and a slight bitterness that “takes the edge off the shoyu’s saltiness.”

The vanilla in particular was important, he said, because it offered a fuller, rounder flavor, while actual sugar would have turned the shoyu into a teri sauce.

“It’s all about balance,” he said.

The takeaway is that a great end product is imbued with a variety of flavor notes: sweet, bitter, acidic, spicy. Shinsato said introducing those notes is best achieved by steeping items in the shoyu, which allows for easy control.

So, armed with my add-ins — konbu, fresh lemon peel, dried fruit and chili peppers — I thought I’d give it a try.

My finished shoyu doesn’t come close in complexity or subtlety to the Shinsatos’ version, but I think it’s a decent first try and an interesting alternative for seasoning when straight shoyu doesn’t quite hit the mark.

I love sprinkling smoked shoyu on everything from stir-fries to my daily hard-boiled egg. Amy Shinsato marinates mozzarella in her smoked shoyu. The possibilities are endless.

Though the Shinsatos use a smoke infuser to do the job, Glenn Shinsato’s suggestion is to use a Weber-type grill.

The key is low heat, with charcoal pulled to one side of the grill to heat the wood chips that provide the smoke. The shoyu sits on the other end. With the grill covered, the shoyu reaps the benefits of the trapped smoke without being subjected to direct heat.

Shinsato advised using Yamasa brand shoyu, a good middle ground between Aloha brand, which he deemed “kinda light,” and Kikko­man (“salty”).

I turned to my grillmaster brother-in-law, Darren Kimura, for help. He heated his Weber to a low 175 degrees by placing the charcoal in a cage to keep it contained to one side. I had two containers of shoyu: A wide, shallow baking pan so the smoke could hit a greater surface area, and a Mason jar, for the purpose of comparison. We used guava wood chips.

Shinsato had warned that because I was tending the fire, my taste buds would be impaired by the smoke, and he recommended having someone else taste the shoyu to determine when it was done. But since I visited the grill only to replenish the guava chips, I felt confident in my tasting capacities.

After two hours, the minimum smoking time, I went out to test a few drops of shoyu from the pan. It hardly tasted smoky. I called it a day after 3-1/2 hours.

I let my smoked shoyu sit for a couple of days before I began the steeping process. I wanted to give my olfactory system a chance to clear out any traces of smoke.

In hindsight, this is what I know: Heed Shinsato’s advice. A tiny taste of the pan shoyu had me literally shuddering. Not only was the smokiness overbearing, the shoyu had become irreparably concentrated from the lengthy stay in the heat. Clearly, my tasting abilities had been shot.

With the pan shoyu unusable, I focused instead on the shoyu in the Mason jar. It was nicely smoked, though I watered it down with a 1-to-3 ratio of shoyu to water.

My advice: Smoke your shoyu for two hours and move on.

BEFORE YOU SMOKE

Select an appropriate wood chip — the Shinsatos used apple wood; I used guava. Avoid kiawe and hickory, which could impart bitterness. Soak a few handfuls of chips in water several hours before smoking time.

Heat charcoal on one end of the grill for a low heat of under 200 degrees. Place a handful of chips onto a sheet of foil, fold it into a packet and poke a few holes into it. Place packet over the charcoal.

Place pan of shoyu on opposite end of grill and cover the grill. A wide, shallow pan means smoke can hit a greater surface area of shoyu. Monitor temperature gauge. Try to keep heat at about 175 degrees. Add more wood chips as necessary (check every half hour or so).

After two hours, remove shoyu from grill and have someone away from the grill taste for smokiness. If necessary, return to grill and retaste every 30 minutes. If no one is there to taste it, I recommend removing shoyu after two hours.

ALSO WORTH SMOKING

Add bowls of cheese and salt to the grill. After 90 minutes, even the least expensive cheese becomes a heavenly taste experience. Shinsato suggests letting the cheese sit a week in the fridge to allow flavors to bloom. Salt takes a bit of time, three to four hours, to retain smokiness, but it’s nice as well.

STEEPING

To start, taste your smoked shoyu. If it’s too salty, water it down to taste. Consider items to steep that will add a range of flavor attributes: acidic, sweet, bitter, umami, spiciness.

The goal is balanced flavor. Steep one or two items at a time. Check on flavor after about 10 days of steeping, and recheck every couple of days afterward until you hit the desired levels of flavor.

Add more items and repeat the process. Keep shoyu refrigerated once you begin steeping.

Items to consider: Alcohol, vinegar, mirin (Japanese sweet rice wine), tea, konbu, citrus peel, shiso (also called perilla or beefsteak plant), dried fruit (fresh clouds the liquid), vanilla.

Here’s what I did:

>> Konbu: A steep of about about 2-1/2 weeks added body and rounded flavor but also more saltiness, so I had to dilute the shoyu further. A good alternative: Boil the konbu first to cut back the salt.

>> Lemon peel: Amy Shinsato advised using just the peel without the pith, which can be bitter, then squeezing and bruising the peel to release its oils. I cut a strip several inches long. A month of steeping imparted a nice tangy balance to all that saltiness.

>> Dried apricot: To impart sweetness, I wanted to try dried mango, but every version I found had added sugar. Since I sought a subtle sweetness, I went with the apricot, a good choice. It steeped about three weeks.

>> Dried japones chili pepper: After much experimentation, I found that cutting a long slit along the length of the pepper allowed the spiciness to release efficiently into the liquid. After a week, my shoyu was infused with a lively, but not overpowering, heat that blooms slowly on the palate yet does not linger — nice.

Is there a cooking technique you’d like explained? Email food editor Joleen Oshiro, joshiro@staradvertiser.com.