For the rice:
In a rice cooker, combine the rice, coconut milk, water, salt and sugar and mix to combine. Cover and set to cook. Once cooked, fluff the rice and keep warm until ready to assemble.
For the cucumber:
Mix together the vinegar and sugar in a shallow dish or bowl. Add the cucumber and toss to coat. Let it sit while you prepare the salmon.
For the salmon:
Preheat the oven to broil on high (550°F).
Place the cubed salmon in a large bowl and add the oil, through to the nanami togarashi (if using) and toss to combine.
Transfer the salmon to a large rimmed baking sheet. Place in the oven and broil for six to eight minutes, depending on your preference, until slightly browned and cooked through.
For the spicy mayo:
While the salmon is cooking, make the spicy mayo. In a small bowl, mix together the mayonnaise, sriracha and lime juice.
To assemble:
Divide the rice into bowls and top with cucumber and salmon. Add the avocado and garnish with furikake and chives. Drizzle the spicy mayo over the salmon and season with salt if needed. Enjoy!