In a small bowl whisk together the cumin, the vinegar, and salt to taste and whisk in the olive oil. In a bowl combine the beans, the tomatoes, the avocado, peeled, pitted, and cubed, and the scallion, stir in about two thirds of the dressing and salt and pepper to taste, and toss the mixture well. In a small skillet heat 1/2 inch of the vegetable oil over moderately high heat until it is hot but not smoking and in it fry the tortillas, 1 at a time, for 1 minute, or until they are crisp and golden, transferring them as they are fried to paper towels to drain. In another bowl toss the curly endive and the cabbage with the remaining dressing and salt and pepper to taste. Divide the tortillas between 2 plates, top them with the black bean mixture, and divide the curly endive salad between the plates. Serves 2. Gourmet May 1993