Slice spam into 0.5cm thick pieces.

Heat a pan with oil and fry spam until golden on both sides.

Place fried spam on a paper towel to remove excess oil.

Mix vinegar, sugar, and salt to create sushi vinegar.

Spread hot rice on a steamer and drizzle half of the sushi vinegar evenly. Mix well.

Shape rice into bite-sized portions using your hands. Use remaining sushi vinegar on your hands to prevent sticking.

Prepare wasabi by mixing powder with water and place a small amount on each rice portion.

Combine chopped onion, mayonnaise, vinegar, sugar, and pepper to make topping sauce.

Thinly slice onion and rinse under water. Dry with a paper towel.

Place fried spam on rice and wrap with a strip of nori.

Spread topping sauce on spam, leaving the edges clean.