Cut cauliflower into large florets. Bring a large saucepan of water (at least 2 quarts) to a boil; add 2 teaspoons salt or to taste. Add florets and cook at a rolling boil about 3 minutes. Drain and plunge into ice water to stop cooking. Drain again and dry on paper towels.

Combine flour with ½ teaspoon salt (or to taste) and a generous grinding of pepper in shallow tray or deep-rimmed plate. In heavy saucepan or deep-fryer, heat oil to 375°F. While it is heating, beat egg whites in mixing bowl until stiff but not dry. Add yolks, one at a time, beating well after each addition. Have salsa ranchera ready, heated just to a simmer.

Roll the flowerets in seasoned flour. When oil is heated, shake off excess flour, dip florets in egg mixture, and fry in batches until golden. Do not crowd pan; watch temperature to be sure it stays close to 375°F. Remove each batch as it is done and drain on paper towels. Pour salsa ranchera over hot cauliflower and serve at once.