A classic joke about a classic meat-replacement product. I’ve known seitan since my childhood where we used to get it from the local eco-hippy-esque store, as the vegetarian option alongside “boerenkool” or “hutspot” (traditional Dutch dishes of mashed potatoes+vegetables; kale for the first and carrot+onions for the second). We used to coat a thin slice of seitan in flour and fry it to create a crunchy layer on the outside, yum! Shortly after moving to the UK, I found myself in a pub looking for vegan options on the menu. They had a “Hail Seitan” burger, exciting and a pretty funny joke the first time! Imagine my disappointment in the tasteless thick slab of cold seitan I received…
Seitan really is a very versatile product so naturally the quality of your meal highly depends on how it is prepared. In essence, the only two ingredients needed for seitan are gluten flour (aka “vital wheat gluten”) and water. This creates a very sticky dough, which can then be boiled or steamed to cook. After that it’s edible, but usually this is the basic ingredient which can be cut and prepared in different ways (I guess this is something the “Hail Seitan” cook didn’t know about). The basic recipe of gluten flour + water is pretty tasteless, but flavours can be added in different ways: spices in the flour, soy sauce and the like to replace some of the water, and broth for boiling. After experimenting a bit I created an improvised seitan kebab which I was very pleased with, so I’ll share the recipe here.
[EDIT] I have a bit more experience making seitan now, so I have updated the recipe with what I think are improvements!
(Enough for four pitas)
For the seitan dough:
150 g of gluten flour (aka vital wheat gluten)
40 g chickpea flour (aka gram flour)
1 tsp onion powder
1/2 tsp garlic powder
2-3 tsp paprika/smoked paprika (you can use a mix and adjust depending on how much smokey flavour you want)
pinch of salt
~tbsp soy sauce
~100 mL water
water for cooking
For the sauce:
140 g tomato puree
1 tsp sambal oelek (or other spice paste like toban djan. Adjust based on your desired 🌶️🌶️🌶️ level, 1 tsp sambal gives it a bit of a kick but nothing crazy)
juice of one lemon
1-2 tbsp soy sauce
1 tbsp maple syrup
Any oil for frying
Making the seitan. Mix the gluten flour, chickpea flour, spices and salt. Stir the soy sauce in ~50 mL of water and add this to the dry ingredients. Stir or kneed with your hands and gradually add only as much water as needed so all the flour is hydrated and you have a cohesive, lumpy dough (as in the first picture below).
Flatten your lump and pack it in aluminium foil. Place in a pan and add water to cover it. Cook for about half an hour until it’s done. It’s okay to cut the seitan after a while to check — there should be no more raw dough in the middle — and cook it without foil for longer if necessary.
Alternatively : In a pan that can easily contain your seitan lump (it will expand while cooking), heat up some vegetable broth. Place your seitan in it and cook until it’s done in about half an hour (you should be able to see a colour change). To reduce the cooking time, you may cut the seitan into a few thick slabs halfway through. 
Making the kebab. Slice the cooked seitan into thin pieces. They don’t have to be regularly shaped. I like to cut the seitan slabs as an angle (see the second picture below). Drain any liquid from the seitan slices with a clean tea towel (or paper towels).
Prepare your sauce by mixing all the ingredients. Taste and adjust the flavour: more lemon juice for sour, more soy sauce for salt, and more maple syrup for sweet .
Fry the kebab slices in some oil for a few minutes. This step is not strictly necessary as the seitan is already cooked, but it’s where you can get a bit of browning and crispiness. Then add the sauce and a splash of water. Cook the sauce down to reduce it, cooking the tomato puree in the process, stirring frequently.
Serve. Serve however you like, for example in a toasted pita. The bread is mainly carbs and the seitan in mainly protein (gluten flour is 75% protein by weight), so I like to serve vegetables on the side. Bonus recipe for the salad from the picture at the bottom!
-  The first method gives you the best structure for “kebab” slices, nice and compact. However, I wanted you to know it’s totally possible to cook seitan without aluminium foil (it will expand more, and soak up some of the cooking liquid). I suggest using some vegetable broth for flavour but plain water will work just fine.
-  You can store the cooked seitan in water/broth in a closed container in the fridge. Not exactly sure how long it will keep, but this will allow you to split the work onto different days. You could also make more seitan to use in different recipes!
-  A smart person would not add all their available lemon juice in one go, but save some for the adjustments. The quantities given in the recipe are really just a guess so tasting is strongly recommended! Do note however, that at this point the tomato puree is still raw, so the final sauce will not taste exactly the same (it will be better). But you can definitely balance the basic flavours (salt, sour, sweet) at this point.
My favourite green salad (thanks mum!)
green beans, cooked
olives (green or black)
good quality olive oil (we are adding this for flavour, so it had better taste good)
Halve the green beans and the olives. Peel the avocado (not the cucumber, do you really want to remove most of the flavour?!) and cut it and the cucumber into chunks. Mix the veg with some olive oil and salt (less salt if you’re using black olives, because they are saltier by themselves).