Process cauliflower and cucumber in a food processor until they resemble small grains.

Combine cauliflower-cucumber mixture in a bowl with lemon juice, salt, and pepper.

Mix wasabi, tamari, and sesame oil in a separate bowl.

Pour the tamari mixture over the salmon cubes and combine.

Assemble the poke bowls by layering cauliflower-cucumber rice, salmon, and avocado.

Cut nori sheets into strips and place on top.

Drizzle with sesame seeds.