St. Francis first produced Cabernet Sauvignon from purchased grapes in the 1985 vintage, and the winery has since produced relatively limited quantities of this varietal. The initial vintage was the result of a decade's search for a source of grapes of the quality and character Joe Martin had in mind. Fruit originates from four different vineyard areas, each of which contribute distinct and individual qualities to the finished wine. The Dry Creek Valley yields grapes of rich varietal character and moderate tannins; grapes from the Alexander Valley are soft and fruity; Sonoma Valley and Sonoma Mountain grapes lend the wine color, tannin and body. Harvest for this late-ripening variety takes place from October through late November.

The fruit is hand-harvested, brought to the winery and crushed into temperature-controlled stainless steel tanks. When the tanks are two-thirds to three-quarters full, the must is inoculated with selected yeasts and yeast nutrient. Fermentation takes place at temperatures of up to 85 to 90F over a period of eight to 15 days, and once fermentation is underway, the juice is pumped over the cap of skins three times daily for a half hour each to extract maximum color. Toward the end of the alcoholic fermentation, a culture is introduced to initiate the malolactic fermentation; the wine is pressed from the skins into fresh stainless steel, where malolactic fermentation is completed over four to six weeks. The lots are racked into new and one year old American and three and four year old French oak barrels for an aging period of 14 to 16 months. Depending on the vintage, origin of oak is in proportions of 20 to 40 percent French oak, which lends refined, toasty, vanilla notes; and 60 to 80 percent American oak, which contributes tannic structure and cedar and tobacco notes. The barrels are topped roughly once every three months. At the end of the term in oak the blend is assembled, usually without filtration. In the event the wine has not clarified sufficiently in barrel, it is given a light passage through a coarse pad filter. The wine is then bottled and held for four to eight months prior to release.

St. Francis Sonoma County is styled to emphasize rich varietal character and body in a classic Sonoma style. The fragrant Cabernet aromas of cassis and black fruit are underscored by discreet notes of vanilla, cedar and tobacco, and carry into ripe, intense berry fruit flavors on the palate. The structure is firm and well balanced, with excellent depth and supple, generous tannins. These impressions are confirmed on the finish, which is long and marked by a complex notes of spice and oak.