Start by rinsing the jasmine rice until the water runs clear. This step keeps the grains separate and fluffy. Add rice, coconut milk, water, salt, and coconut sugar to a rice cooker. Cook according to instructions, then fluff and keep warm.
In a bowl, mix rice vinegar and white sugar until dissolved. Add thin cucumber slices and let them sit while you prepare the salmon. They will become lightly tangy and refreshing.
Preheat oven to high broil (about 550°F). Toss cubed salmon with avocado oil, tamari, sugar, garlic powder, ginger, sesame seeds, and optional spice. Spread on a baking sheet and broil for 6–8 minutes until browned and cooked through.
Combine mayonnaise, sriracha, and lime juice in a small bowl. Stir until smooth and creamy. Adjust spice level to taste.
Divide coconut rice into bowls. Top with salmon, pickled cucumbers, avocado slices, and furikake. Drizzle with spicy mayo and garnish with chives before serving.