Cardoons, swiss chard, eggplants, zucchini, asparagus, and other vegetables, whether cooked alone or as part of a more elaborate presentation, are typically served as a first course in Spain, rather than as an accompaniment to a main course (a main-course accompaniment is usually roasted or fried potatoes, potato purée, or white rice). Since some of these vegetables dishes, such as the mixed-vegetable menestra de verduras from Navarra, require a lengthy preparation - often far longer than grilled meats or fish - it's fitting that they receive special attention at the table.
However, many of these first
courses could indeed make wonderful accompaniments in the American sense. For
example, in Spain, the classic La Mancha stew, a simple blend of tomatoes and
peppers, is often served with fried or scrambled eggs as a first course for
lunch or dinner, but it would go well with grilled fish or meat as a side dish,
too.
And the versatility of these dishes, despite their prescribed place on the Spanish menu, does not end there. Most of these first courses can be served as main courses by simply increasing the portion size.