Remove the thin membrane from the fava beans. Cut the each chicken tender diagonally into 5 pieces, and lightly season with salt, pepper and garlic powder (optional). Slice the onion into rounds to make onion rings.
Put 1 cup of store-bought tempura flour into a bowl, pour the beer, add salt and grain mustard, and mix well. Deep-fry the battered onion, fava beans, and chicken tenders in that order in 170℃ oil. (Since the chicken tenders are seasoned with garlic powder, deep-fry at the end, so that the other things won't absorb the smell).
Cut 1/2 of avocado into small pieces, sprinkle with lemon juice, and mix with mayonnaise. Pass the mixture through a strainer, and add wasabi little by little to make your desired spiciness. Mix well after each addition. Serve the beer-battered fries with this dip.
For grainy mustard, if you find cassis mustard, it's worth trying it to make this dip! It's grainy mustard with the cassis aroma (not sweet), and has a refreshing flavor. You can use the leftover to make a salad dressing or sandwich, or serve with meat dishes.