SOMETIMES diners see things they're not supposed to: a cook probing the interior of his nostril, a wayward dishrag on a restroom floor, a catfight between a hostess and a patron. Rarely, though, does an unintended discovery cause a diner to smile, impressed by something she wasn't supposed to see in the first place.

This is what happened when I glimpsed a whiteboard behind closed doors in the back of jZcool Eatery & Wine Bar in Menlo Park. I wasn't snooping, but I could see through a sliver of glass the words "fresh, local, sustainable, organic" inked on the staffroom board.

It's no secret that this mantra forms the backbone of owner Jesse Ziff Cool's philosophy: The eatery's commitment to sustainability is emblazoned in tidy green and gold lettering as soon as you walk in the door. But that's for diners; they're supposed to see it. When it's also inscribed for the staff in a closed-off room down a dimly lit hallway, it suddenly turns from savvy marketing-speak to principled authenticity.

jZcool is the new incarnation of Cool's former deli at the same location and she describes the remodel as one of the hardest she's ever done. (She owns two other local restaurants, Flea Street Café in Menlo Park and the Cool Café in Stanford's Cantor Arts Center.) According to Cool, longtime deli patrons were "shocked" by the new format since they were so used to eyeing their food before ordering.

Cool's manager is 22-year-old Talia Vardi. Her skill at transforming local, organic and sustainable ingredients into flavorful, fully realized dishes is apparent in nearly every dinner item I tried. Among the highlights were two starters: the golden fried arancini ($5), three crispy-on-the-outside, creamy-on-the-inside orbs of rice filled with smoky mozzarella and a single sun-dried tomato, and the grass-fed sliders ($11), miniburgers sandwiched between sesame seed–topped biscuits so fluffy and light you'd swear the chef had apprenticed in the deep South. The house-made pickle and plumped-up raisin and roasted red pepper chutney were perfect accompaniments.

As for entrees, a fillet of Pacific salmon ($19, a catch of the day) coated with olive oil and grilled yielded such a silky finish I could have sworn it was drizzled with butter. (Cool assured me it was not.) Toasted herbed bread-crumbs and more slivers of sun-dried tomato lay on top. Happily, you won't find fresh tomatoes here in winter given Cool's staunch commitment to seasonality.

Another star entree was the pasture-raised chicken breast stuffed with creamy goat cheese, tangy preserved lemons and salty olives ($16). The bright burst of complementary flavors put your average restaurant chicken breast to shame.

Dinner service has a number of upscale touches that make the eatery feel semisophisticated while still creating a relaxed, neighborhood-style atmosphere. Red votives flicker throughout the space and service is exuberant but completely professional. Accompanying the wine flights (all organic, $12 for three pours) are smooth stones with the name of each wine written in flowing silver letters. World music pumps on the sound system. Dim lighting adds drama.

Lunch is much more casual. You order at the counter, pick up silverware and napkins yourself and servers deliver your order to the table. The fennel-basil soup ($7) underwhelmed me, but the seafood chowder ($8), seemingly little more than a can of olive oil–packed tuna and a few calamari rings afloat in a gentle broth, captivated me with its simplicity. A meatloaf sandwich ($9) with bacon and mint pesto was terrific.

Desserts include assorted cookies at lunch (made off-site by Cool's ex-husband Bob) and, at dinner, a moist slab of bread pudding with pomegranate seeds and a so-so pear-apple "cobbler" (it was actually a crisp), both $7.

A word regarding serving sizes and pricing: You'll spend slightly more here than at your typical neighborhood hangout, and portion sizes are decidedly small. But with a change of perspective you'll realize you're paying for the purity of the ingredients rather than their quantity. (Even staples like flour, butter and herbs are organic, so it's no surprise food costs are high). Small portions mean you can also eat a number of different dishes without feeling like you're going to blow.

"We follow the European model of serving delicious but sensible amounts of food," Cool explains. "Our portions are designed so you can eat a couple of courses."

Cool hopes diners will appreciate her commitment to locally sourced, hormone- and pesticide-free food and wine and be willing to pay a few bucks more for it. With food this flavor-packed and beautifully prepared, they will.