Spicy Tuna Onigiri

and 1/2 cups (2 rice cooker cups) Japanese short-grain (sushi) rice

cold water

kosher salt

each) cans Bella Portofino Solid Albacore Tuna in Extra Virgin Olive Oil, drained

and ½ tablespoons mayonnaise

sriracha hot sauce

rice vinegar

scallion, green parts only, finely sliced

toasted black sesame seeds, for sprinkling (optional)

sheets of toasted nori, cut crosswise in half