Tender greens with somewhat assertive flavors, such as peppery arugula and watercress or bitter endive, or young dandelion go wonderfully with sweet citrus fruits like oranges, mandarins, and blood oranges, ripe pears or crunchy apples, and figs. Roasted nuts bring out the sweetness in the greens. There are endless possible variations on this theme. One of my favorites is arugula, blood oranges, and roasted pine nuts. Or, for an easy main-course luncheon salad, combine frisée, quartered ripe figs, and walnuts, then top it with thin sheets of prosciutto or smoked goose breast.