The highest amounts are found in seed oils, especially flaxseed. Lignans are also found in some grains. They become biologically available when bacteria in the intestine acts on the digested grain. You have probably eaten tofu and not realized it. It is common in Asian cooking.
Firm consistencies are good to use cubed served in soups, stir fried or grilled.
Firm tofu is higher in protein, fat and calcium than other forms of tofu. Soft tofu is good for recipes that call for blended tofu. Silken tofu is a creamy product that is a good replacement for sour cream in many dip recipes. You can purchase tofu in most grocery stores. It's made of curdled soymilk and has a custard-like consistency.