This is admittedly a fairly labor intensive recipe, but it is a wonderful vegan appetizer that shows off the amazing flavor of tomatoes. For more variety, you can make a simple cucumber/avocado roll, and serve slices of that alongside the tomato sushi.
To make the sushi rice:
Wash 2 C. white Sushi rice until the water is clear.
Place in a pot with 2 1/2 C. water. Bring a boil, then cover and simmer on low for 6-8 minutes, until the rice is done.
In a small saucepan, mix together 1/3 C. rice wine vinegar, 1 t. salt, and 1/2 t. sugar. Simmer over low heat until the salt and sugar are dissolved. Pour the mixture over the still-hot rice, and stir it well to combine. Allow the rice to cool at room temperature — do not refrigerate.
To make the Tomato Sushi:
Bring a pot of water to a boil. Cut an “X” in the skin on the bottom of 2-3 ripe tomatoes. Using a slotted spoon, dip each tomato into the water for 10 seconds. Use the cut section to peel off the skin in large pieces.
Cut each tomato into sushi-sized segments. Scoop out the gel and seeds and set aside.
Place the tomato skins in your oven or toaster oven on a baking sheet, brushing lightly with oil. Toast them very lightly, until just crisp. When they cool slightly, cut them into strips.
Form balls of the cooked, seasoned rice, then press them into sushi-shape. Brush each with a small amount of wasabi paste (optional), then top with a piece of tomato sushi.
Top each piece of sushi with a small amount of tomato gel/seeds, toasted tomato skin, toasted nori seaweed, flaky sea salt, and toasted sesame seeds (preferably black ones).