How to make roast beef: A recipe for making beautiful and clean roast beef. Roast beef sandwiches

Hello everyone.
Today, I want to make a beautiful roast beef, so I'd like to share with you the recipe I came up with after researching every morning!
Try making this as a treat for entertaining guests or as a treat for yourself✨
Setouchi Living🏖️ Instagram for retro cuteness↓
🌷: / marino831
Roast beef
350g beef thigh
Salt to taste
Salt and pepper to taste
Sauce
1/8 grated onion (about 1/4 tablespoon)
Sugar 1 tablespoon
Mirin 3 tablespoons
Sake 3 tablespoons
Koikuchi soy sauce 2 tablespoons
Ponzu 1 tablespoon
Roast beef sandwich
Yama-shoku bread (5 slices) 2 slices
Butter 10g x 2
Mayonnaise to taste
Frill lettuce 2 slices
Roast beef 5 slices
Sauce to taste
Cheddar cheese 2 slices