For the sauce:
- In a medium mixing bowl, combine all the ingredients for the sauce: green onions, soy sauce, sesame seeds, sesame oil, rice vinegar, ginger, garlic, sriracha, and salt. Set aside for now.
- In a large skillet, heat the ½ tablespoon of sesame oil over medium heat. Add the chopped watermelon and cook for 6 to 9 minutes, stirring occasionally, until most of the excess liquid in the pan has evaporated and the watermelon has deepened in hue slightly. Let cool for a few minutes.
- Remove the watermelon from the pan and toss in the mixing bowl with the sauce. Pour the mixture into a flat glass container or food-safe ziptop bag, and place in the refrigerator to marinate for about an hour.
- Meanwhile, in a mixing bowl, prepare the base of the tartare by combining the avocado, jalapeno, cucumber, lime, and salt. Keep chilled until ready to use.
- When the watermelon is done marinating, prepare the tartare stacks by using a round food mold (or a biscuit cutter). First place in the cucumber avocado base until halfway full. Then use a slotted spoon to remove the watermelon from the sauce mixture, and place it on top of the cucumber avocado mixture. Press down slightly with the top of the food mold or the back of a spoon, then remove the mold. Repeat for each stack.
- Enjoy! Feel free to add an additional drizzle of sriracha on the plate if desired.
- Speed up the watermelon cooling process by placing the mixture in the freezer for about 30 minutes instead of in the fridge for an hour.
- If there’s excess liquid on the plate from the sauce when preparing the stacks, just use a paper towel to soak it up and wipe the plate clean.
- Leftovers can be stored in the fridge for up to 3 days for best quality. Note that the avocado may brown due to oxidation over time.
- Serving size