Thinly slice the red bell pepper. Peel and cut the asparagus into thirds. Microwave asparagus in a covered container for 30 seconds at 600W and let cool.

Lay 2 slices of beef flat, season with salt and pepper, sprinkle with flour, and place red bell pepper, asparagus, and baby corn on top. Roll tightly. Repeat with another 2 slices of beef to wrap the first roll. Make a second roll similarly.

Heat vegetable oil in a pan over medium heat. Place the rolls seam-side down and cook until browned, turning occasionally. Add sake, cover, and steam on low heat for 2 minutes.

Dice the potato and soak in water briefly. Drain and microwave in a covered container for 5 minutes at 600W until soft.

Mash the cooked potato while hot, adding butter, milk, and seasoning. Mix until smooth.