Cut a cucumber into long thin strips or match sticks.
Shred imitation crab into a container.
Spoon in mayonnaise, lemon juice, and a few drops of sriracha or yr favorite hot sauce. Mix them well.
Cover and chill in the fridge for 10-20 minutes.
Season sushi rice with sushi vinegar OR an equivalent amount of rice/apple vinegar plus 1 tsp of sugar and ¼ tsp of salt.
Cover your bamboo mat with plastic wrapper and place it on a flat surface.
Lay another piece of plastic wrapper atop the bamboo mat.
Tear a sheet of nori down to ¾ and layover plastic/bamboo mat.
Spread rice all over nori, then flip the whole sheet over so that the nori side is facing up.
Spoon in the crab salad and arrange cucumber slices.
Lift, tuck, and roll into uramaki sushi roll.
Create a layer of crab salad on one end of the plastic wrapper.
Then lay the sushi roll on top of it.
Carefully roll again, this time the crab salad will cover the top of sushi roll creating a nice marble snow effect.
Cut into bite-size slices.
Unwrap and sprinkle some sesame seeds before serving.
Either serve immediately or chill a couple of minutes for cold & refreshing effect at the bite