SUMMER IN SAN Francisco has settled in. Meaning fog and afternoon gusts of wind. The mist turns so thick the cement is wet, and this morning I saw someone pop open a pink umbrella on Judah Street. Mark Twain's infamous quip on the quality of the season in this city plays on a loop in my heavy head.

It seems faintly ridiculous to see shop window displays crammed with strapless dresses in delicate floral prints. I suppose they're for those brave warm-blooded souls who adhere firmly to seasonal precepts no matter what the reality of our microclimate is. We pass one another on the streets – they determinedly bare limbed, and I bescarfed.

Stone fruit and lychee are consolations, but my stomach sends emissaries demanding heat-bearing sustenance. Carrot-ginger soup, ratatouille, and for breakfast, buckwheat.

Buckwheat is often referred to as having "an assertive flavor" – a descriptor that brings to mind a tearoom full of Victorian ladies averting their eyes from some faintly offensive item. "Assertive flavor" sounds like a euphemism for "difficult." Were I elected to record buckwheat in an encyclopedia of the universe, I'd register it under the heading "Foods of the Gods," in company with artichokes. And lychee fruit. And tomato paste, for that matter.

But back to buckwheat, which is not, in fact, wheat. It is not even a grain. It is an herb related to rhubarb (no wonder I love it), and those amazing 3-D triangles we eat are its seeds. Its origins most probably in Asia, it spread to parts of Europe in the Middle Ages and reached the Hudson River Valley with the early Dutch colonists – which may be why New York state continues to be one of the major buckwheat-producing areas in this country. Buckwheat is an ingredient in many foods of the world (soba, for example) and is especially popular in variations on the pancake (think blini and crepes). Apparently, Tibetans also eat the leaves of the plant, but sadly I've never had the privilege.

"So why is buckwheat a food of the gods?" you may ask – especially those of you wary of its kinship to rhubarb. (Don't worry, it tastes nothing like its relative.) My favorite way to consume it is in the form of toasted whole groats, boiled to the softer side of al dente, served with milk and salt, as my first meal of the day. Forget Wheaties – this is the true breakfast of champions: a rich, nutlike flavor, intriguing tricornered texture, and a bowl of it packs more nutrients than you can shake a stick at. Buckwheat is even regarded as a "neutraceutical": i.e., a food or food ingredient that acts as a medicine. For reasons I can't yet fully articulate, I'm leery of this concept – in part because of the American tendency to fixate on some supposedly beneficial element while ignoring a broader context (along the lines of Kool-Aid advertising itself as a great source of vitamin C).

The substances that give buckwheat its medicinal reputation are rutin (beneficial to blood vessels and helps lower blood pressure and cholesterol) and fagopyritol (helps stabilize glucose levels in diabetics). It's a great food for vegetarians because, unlike grains, it contains all eight amino acids and supplies a significant amount of lysine – the hardest amino to come by in grains. It's possibly the best and most digestible plant source of protein – even better than soybeans (but why make them compete when they're both so tasty?). Buckwheat is also low in fat, cholesterol and gluten free, high in fiber, and a source of vitamin B, potassium, phosphorous, magnesium, manganese, and linoleic acid.

After that litany I imagine you've dropped the paper and are running out the door to buy up all of the buckwheat you can get your hands on. Or you have vowed not to let a kernel of this goody-two-shoes food pass your lips. Buckwheat's formidable résumé aside, try it and see if the flavor doesn't win you over.

Buckwheat can be bought in an array of unadulterated forms, besides my favorite, toasted groats: raw groats, flour (excellent mixed in with regular flour for pancakes and waffles), unhulled groats (used mainly for sprouting), and grits (ground groats). Grits are fine, but you lose out on the texture of the whole kernel, a hearty sensation rivaled only by steel-cut oats, and those take an eon to cook.