Pre-heat oven to 220C.
Mix mayo and mentaiko together. Transfer into ziplock bag.
Line baking sheet with non-stick paper or oil baking sheet to prevent sticking.
Place salmon on baking sheet, drizzle olive oil, season with salt and black pepper.
Bake for 6 - 7 minutes.
Snip the edge off the ziplock bag and pipe mentaiko mayo over the top of the salmon.
Return to oven and broil (keep watch!) or bake for another 2 minutes until bubbly. Or if you have a blowtorch, you can blowtorch the top the mentaiko mayo until bubbly and/or browned.
Garnish with spring onions, pickled ginger, and lemon wedge and serve.