Begin by preparing your tofu (Magsimula sa paghahanda ng tokwa). Remove the tofu from its packaging and drain well. Place the tofu blocks between several layers of paper towels and put a heavy plate or pan on top. Let it press for 20 minutes to remove excess moisture (Patuyuin ang tokwa sa loob ng 20 minuto).
While the tofu drains, finely chop your onion (sibuyas), mince the garlic (bawang), and dice your red and green bell peppers (siling pangsigang) into small, even pieces. Slice the finger chilies (siling haba) thinly and mince the Thai chilies (siling labuyo) if using. Set all vegetables aside.
Cut the pressed tofu into small ½-inch cubes (Hiwain ang tokwa ng parisukat, kalahating pulgada ang laki). Heat your canola oil in a deep pan or wok to 350°F (175°C). You'll need enough oil to submerge the tofu cubes.
Gently drop the tofu cubes into the hot oil in batches, being careful not to overcrowd the pan (Iprito ang tokwa ng pakonti-konti). Fry each batch for 5-7 minutes until golden brown (Iprito hanggang magkulay ginto). Remove with a slotted spoon and place on paper towels to drain excess oil.
Preheat your sizzling plate in the oven at 450°F (230°C). This ensures a proper sizzle when serving (Initin ang sizzling plate sa mainit na temperatura).
In a large pan over medium heat (350°F/175°C), melt the butter (Tunawin ang mantikilya). Add minced garlic and sauté until fragrant, about 1 minute (Igisa ang bawang hanggang mabango). Add the chopped onions and cook until they become translucent, about 3-4 minutes (Igisa ang sibuyas hanggang maluto).
Add the diced bell peppers and chilies to the pan. Cook for another 2-3 minutes until the peppers are slightly softened but still crisp (Idagdag ang mga sili at lutuin ng 2-3 minuto).
Pour in the Knorr Liquid Seasoning and calamansi juice (Idagdag ang Knorr at katas ng kalamansi). Stir well to combine. Season with salt and pepper to taste (Timplahan ng asin at paminta).
Add the fried tofu cubes to the pan and gently toss everything together to coat the tofu with the seasonings (Idagdag ang pritong tokwa at haluing mabuti). Cook for another minute to heat everything through.
Remove the pan from heat and fold in the mayonnaise until everything is well coated (Ihalo ang mayonnaise). Don't overmix to keep the tofu crispy.
Take your preheated sizzling plate out of the oven using thick mitts. Carefully transfer the sisig onto the hot plate - it should sizzle immediately. Serve right away while sizzling hot (Ihain habang mainit at umuusok pa).
Optional: Serve with extra calamansi halves on the side and steaming white rice (Maaaring lagyan ng kalamansi sa tabi at mainit na kanin).
For best results, eat immediately while the plate is still sizzling and the tofu is crispy (Kainin agad habang mainit pa at malutong ang tokwa). If you need to store leftovers, keep the components separate and reheat the tofu in an air fryer at 400°F (200°C) or oven at 350°F (175°C) until crispy again before combining with the sauce.