Cook the Sushi Rice: Start by rinsing 1 cup sushi rice under cold water until the water runs clear. In a pot, combine the rice with 1 1/4 cups water and bring it to a boil. Once it’s boiling, reduce the heat to low, cover it, and let it simmer for about 15 minutes, or until the water is absorbed. Once done, remove it from heat and let it sit covered for an additional 10 minutes to finish cooking.
Season the Rice: In a small bowl, mix together 2 tablespoons rice vinegar, 1 tablespoon sugar, and 1 teaspoon salt. Gently fold this mixture into your warm rice. This step is crucial for that authentic sushi flavor! Spread the rice onto a baking sheet to cool off a bit.
Prepare the Shrimp: In a medium skillet over medium heat, cook 1 pound shrimp for about 2–3 minutes per side, until they’re pink and opaque. Once off the heat, let them cool slightly, chop into small pieces, and mix with 2 tablespoons mayonnaise and 1 tablespoon sriracha. You can adjust the spice to suit your taste preference.
Prepare the Avocado: Halve the 1 ripe avocado, discard the pit, and scoop the flesh into a bowl. Mash it gently with a fork and season with a pinch of salt if desired.
Assemble the Stacks: Grab a ring mold or use a small cup. Start layering your ingredients: first a layer of sushi rice, followed by a layer of thin cucumber slices, then a layer of creamy avocado. Finally, top it off with that spicy shrimp mixture.
Garnish and Serve: Carefully remove the mold and give your stacks a little sprinkle of 2 tablespoons sesame seeds and 1 sheet nori pieces on top. If you like, you can also add some sliced scallions for extra color and flavor. Serve these delightful stacks with soy sauce on the side.