Rinse the sushi rice under cold water until clear. Cook rice as per instructions, then let sit for 10 minutes before seasoning.

Preheat oven to 400°F. Peel and dice the sweet potato, toss with olive oil and salt, roast for 25-30 minutes.

Slice cucumber and avocado into strips, keep avocado coated with lemon juice.

Lay nori on the sushi mat, wet hands, spread rice, add sweet potato, cucumber, avocado and sesame seeds.

Roll tightly, seal with water. Slice into pieces, serve with soy sauce and wasabi.