Best Philadelphia Roll Recipe - How To Make Philadelphia Sushi

Ingredients

• 1/2 small red onion, thinly sliced
• 1/2 c. unseasoned rice vinegar
• 2/3 c. sushi rice
• 2/3 c. water, plus more for rinsing rice
• 1 (2") piece kombu (optional)
• 1 tbsp. unseasoned rice vinegar
• 2 tsp. granulated sugar
• 1/4 tsp. kosher salt
• 2 sheets nori
• 2 tbsp. everything bagel seasoning, divided
• 4 oz. smoked salmon, divided
• 4 oz. cold cream cheese, cut into 1/2"-thick strips, divided
• 1 Persian cucumber, seeds removed and julienned, divided
• Soy sauce, wasabi, and pickled ginger, for serving