1. 1. Rinse sushi rice under cold water until water runs clear. Combine rinsed rice and water in a medium pot. Bring to a boil, reduce heat to low, cover, and simmer 15 minutes, or until water is absorbed. Remove from heat and let steam, covered, for 10 minutes.

2. 2. While rice cooks, whisk rice vinegar, sugar, and salt in a small bowl. Heat gently until sugar and salt dissolve. Do not boil.

3. 3. Transfer hot rice to a large shallow bowl. Pour vinegar mixture evenly over rice. Gently fold using a cutting motion with a spatula until incorporated. Let cool completely to room temperature.

4. 4. Prepare fillings: slice smoked salmon, cucumber, and avocado. If using cream cheese, soften. Mix mayonnaise and sriracha for spicy mayo.

5. 5. Lightly grease a 10-cup Bundt pan with neutral oil (or line with plastic wrap, leaving overhang).

6. 6. Press about 1.5 cups sushi rice evenly into bottom of pan. Compact firmly with damp hands or spatula.

7. 7. Lay a nori sheet over rice, pressing gently. Arrange half of smoked salmon slices over nori. Add cream cheese (if using) and half of cucumber slices.

8. 8. Gently press another 1.5 cups rice over filling. Compact firmly. Place another nori sheet on top.

9. 9. Arrange remaining smoked salmon, avocado slices, and any remaining cucumber. Drizzle with spicy mayo if desired.

10. 10. Press remaining sushi rice firmly over fillings. Compact top layer well.

11. 11. Cover pan tightly with plastic wrap. Refrigerate at least 2 hours, preferably 4-6 hours, until set.

12. 12. To unmold, remove plastic wrap. Place serving platter upside down over pan. Invert together. Lift pan off. Tap bottom gently if needed.

13. 13. Garnish with sesame seeds and scallions. Slice with a sharp, damp knife. Serve with pickled ginger, soy sauce, and wasabi.