Cook rice according to package directions. Fluff with fork, cover and set aside.
Pineapple Teriyaki Glaze
In a small bowl, combine the cornstarch and water together. Set aside.
To a blender, add all the glaze ingredients (except the cornstarch mixture) pineapple juice, pineapple slices, tamari, rice vinegar, maple syrup, sesame oil, ginger, garlic, sriracha. Blend on high until smooth.
To a small pot over medium heat, add the blended mixture. Bring it to a simmer and lower heat to a gentle simmer. Cook for a few minutes until it slightly thickens.
Stir the cornstarch and water again and add it to the pot. Let it simmer until it thickens up and becomes sticky. About 4-6 minutes. Stir often to prevent burning and turn down the heat more if needed. Remove from heat and set aside.
Heat up Grill Pan over medium-high heat for a few minutes or preheat outdoor grill (make sure grill is very clean). *See note for using grill pan.
Lightly brush cut tofu with oil and season with salt and pepper. Brush the onion and pineapple with oil too.
Once fully heated, brush surface with oil and place tofu, pineapple and onion on the grill You should hear a sizzle when food hits the pan/grill. Let everything sear for 2-3 minutes before moving (it will stick and break if you move it too soon). Now take a peek to check for grill marks. Carefully flip over using a sturdy spatula or tongs and grill the other side.
While the other side of the tofu is grilling, brush the glaze on top of each piece. When the underside has grill marks too, carefully flip the tofu again. Cook for 30-60 seconds to caramelize the glaze and then repeat on the other side. The glaze can burn easily so don't leave it too long.
Remove pineapple, tofu and onions from heat as they are finished. Add more glaze to the tofu. Cut each piece of tofu crosswise into bite-sized pieces. Serve in a bowl over warm rice and side with the grilled pineapple and onions. *Optional: top with green onions, cut cilantro and sesame seeds. Serve with more glaze on the side. Enjoy!
* PRESSING TOFU: wrap a block of tofu in a dish towel and place it on a rimmed plate. Add a cast iron skillet on top (or something equally heavy)and let it drain for 45-90 minutes. Pat dry to remove excess moisture on the surface.The better it's pressed, the easier it will be to grill and it won't stick to the pan. You can also use a Tofu Press to make it even easier or you can use Pre-Pressed Tofu. Pressing tofu makes it thinner, so you will have a thicker block if you use the high-protein tofu, so you will get a few more slices out of it. Make sure to keep them about ½-inch thick.* Prep time doesn't include pressing the tofu.GRILL PAN: If you're using a grill pan, you will need to work in batches depending on the pan size. Start with the pineapple and onion first because It makes less mess in the pan. Make sure to brush clean before adding the tofu though or it will stick. Brush with oil before for each batch too. Some smoke is ok, but if the grill pan is overly smoking, then your pan is too hot. Lower or remove from heat if needed.