Any idea how to incorporate more fat into seitan? With the purpose to bind flavor for richer and more complex taste, similar to beef.
Without knowing what specific recipe you're starting from, it's hard for me to say exactly. However, there are definitely recipes out there that call for olive oil as an ingredient in seitan (for example: Viva Vegan by Terry Hope Romero, pg. 35). You could try increasing that amount to see what happens, possibly decreasing the broth to keep the same amount of liquid.
Depending on what kind of flavor you're going for, you could experiment with oils that are higher in saturated fat content. Coconut oil is notorious for having a high sat. fat content, however I don't know if it will impart too much taste into your seitan (unless you don't mind that, of course). You could do an experiment with adding melted margarine or shortening to see what happens in those cases.
On another note, do you make seitan with veggie broth or fake beef broth? That also might be worth looking into if you specifically want a "beefier" flavor. I personally love Edward & Sons Not-Beef Cubes.
I have been experimenting with this very thing, which is how I stumbled on this conversation. Real meat (I'm not a vegetarian so I can easily compare) has a different mouth feel. Deli meat feels stretchy and fatty, which seitan never does. It's just stretchy. Adding oil to the mix just seems to make the seitan more brittle. My best luck so far is using the Chicago Diner (famous old vegetarian place) method which is to make the seitan straight, cook it, and THEN modify it. So they make and simmer their basic seitan, then slice and THEN marinade based on how they want it to come out. Different marinades for gyros, corned beef, or turkey. I'm having decent luck marinading my veggie ham (that's been cooked and sliced) in oil.
Here's a crazy idea. Freeze a few cubes of Earth Balance or other vegan butter, and blend the gluten flour and cold fat together in a food processor like you were making biscuits. You could also grate the frozen fat and mix it into the flour, being careful not to melt it with your hands.
Steaming or simmering the seitan would likely cause most of the melted fat to run out. But baking, rolling into sausages sealed in foil, or deep frying it could be amazing.
I've been wondering this too. I wanted a texture more like sausage, with little pieces of fat. I've added finely-chopped onions that I'd caramelized in oil, and crushed up pieces of pine nuts. Both are delicious. The texture is still not exactly like sausage but it's closer, and the onions and pine nuts add extra flavor.
Add strips of rice paper. Hydrated of course and or shredded mushrooms cooked first of course baked.. add a lil oil to the mushrooms and it rice paper when incorporating it will give the effect of having a meaty fatty texture.. just a thought learning some new techniques from what I've seen others do.