Gochujang seitan sandwich

Steps

1. In a small saucepan add the vinegar, water, agave, mustard seeds, and salt. Bring to a boil then add the red onion and stir to coat.
2. After 1 minute, turn off the heat and let the onions sit for 10 minutes. Transfer to a container and refrigerate until fully cooled.
3. In a small saucepan add the gochujang, agave, vinegar and orange juice. Heat over medium, stirring constantly for a few minutes. Remove from heat and set aside.
4. In a small bowl add the mayo, sriracha, rice vinegar, and sesame oil. Whisk until smooth and refrigerate until ready to use.
5. In a bowl, combine ½ cup of the flour with gochugaru and sesame seeds. In another bowl whisk the milk, sriracha, and remaining flour until smooth.
6. Coat each piece of seitan in the flour mixture, then dip into the wet mixture, allowing excess to drip off. Immediately return each piece to the flour mixture for a second coating.
7. Lightly spray the seitan with oil and arrange in a single layer in the air fryer. Cook at 200°C for 8-10 minutes, flipping halfway, until golden and crisp.
8. Heat a skillet over medium-high heat. Place the buns cut side down on the dry pan and toast for 2-3 minutes until golden brown.
9. Spread sriracha mayo on the top and bottom buns. Place arugula on the bottom buns.
10. Warm the prepared sauce in the same pan over medium heat for 1-2 minutes, then add the seitan and coat evenly to glaze.
11. Place the sauced seitan over the arugula. Top with kimchi and pickled onions.