Old school kitchen techniques are making a comeback as home cooks rediscover the flavor, skill, and tradition behind classic methods.

Here are six traditional underground ovens from around the world that you need to know about.

Heat oil in a medium skillet over medium-high heat. Add flour and whisk or stir immediately to make a light, white roux. Add milk, stirring to combine until thickened and comes to a boil. Reduce heat ...