1. Preheat the oven to 375°F.

2. If you’re using buttermilk, milk, or yogurt, ignore this step. If not, make the soured milk: Warm the milk gently—1 minute in the microwave is sufficient, just enough to take the chill off—and add the vinegar. Let it rest while you prepare the other ingredients.

3. Put the butter in a medium ovenproof skillet or an 8-inch square baking pan over medium heat; heat until good and hot, about 2 minutes, then turn off the heat. Combine the dry ingredients in a bowl. Mix the egg into the buttermilk, Stir the liquid into the dry ingredients (just enough to combine); if it seems too dry, add another tablespoon or two of buttermilk. Pour the batter into the prepared skillet or pan, smooth out the top if necessary, and put in the oven.

4. Bake about 30 minutes, until the top is lightly browned and the sides have pulled away from the pan; a toothpick inserted into the center will come out clean. Serve hot or warm.

Lighter, Richer Corn Bread.

Use 4 tablespoons (½ stick) of butter (do not use other fat). Increase the sugar to ¼ cup. Use 2 eggs; stir their yolks into the milk and beat the whites until stiff but not dry, then gently stir them into the prepared batter after the yolks and milk have been incorporated.

Corny Corn Bread.

You have some options here: Add 1 cup of fresh or frozen corn kernels or about a cup of creamed corn to the liquid ingredients in Step 3.

Corn and Bean Bread:

I love this: Use 2 eggs and 1 cup buttermilk or soured milk; omit the white flour. Stir 1½ cups well-cooked white beans (canned are fine), puréed and strained, into the milk-egg mixture before adding to the dry ingredients.