Almost all the ingredients in this sandwich, especially the sprouts and avocado, are associated with the health craze of the 1960s and '70s in California. It isn't so much that a Californian created this recipe, but rather that the combination has come to be synonymous with California cuisine. Multigrain bread is part of that trend, and so-called California sandwiches are often vegetarian, as in this version. You could also include slices of turkey with the cheese.
8 slices multigrain bread, lightly toasted
2 ripe avocados, pitted and thinly sliced
8 thin slices Cheddar or Monterey Jack cheese (about 4 oz.)
1 cup alfalfa sprouts
1 large tomato, thinly sliced into 8 slices
1/4 tsp. freshly ground black pepper