Eggplant originated in tropical Asia and was gradually adopted by Indian, Middle Eastern, and Mediterranean cuisines. Now it’s very much at home in America as well. That mysterious dark purple egg-shaped orb has recently been upstaged by its white, pale green, violet, black, lime, orange, and striated cousins, with their long, slender lines or round, plump curves. But eggplants of all colors have subtle, elusive flavor and are at their best when accented by garlic and other robust vegetables, spices, and fresh herbs.