Editor’s note: The theme of Gohan Lab is to help people make simple, tasty “gohan” (meals). * * * Think you know your tofu? What's the difference between “momen” and “kinugoshi” tofu? How heavy is a standard block of it? Despite tofu being such a familiar item, the questions may stump you. Our four-part series starting this week focuses on tofu that tastes good as is and is more savory when cooked. About 90 percent of tofu is water, which many recipes require you to drain before you cook it, at which point you may wonder what's best, to pat it dry or microwave it.