To reduce tempeh's natural bitterness, start by poaching it.
Place the tempeh slices in a skillet, cover with water, and bring to a simmer.
Cook for 7 minutes, then carefully drain and pat the slices completely dry with a paper towel.
Heat the canola oil in the same skillet over medium-high heat.
Add the dry tempeh slices and cook until golden brown on all sides, about 3-4 minutes per side. During the last minute of cooking, add 1 tablespoon (15 ml / 0.5 fl oz) of the tamari to the pan, tossing to coat the tempeh.
Remove the tempeh from the skillet and set aside.
While the tempeh cooks, prepare the sauce.
In a food processor or blender, combine the peanut butter, scallions, ginger, garlic, coconut milk, lime juice, brown sugar, cayenne, and the remaining 1 tablespoon (15 ml / 0.5 fl oz) of tamari.
Blend until the sauce is completely smooth and creamy.
Pour the peanut sauce into the skillet and bring to a gentle simmer over medium heat.
Add the browned tempeh back into the sauce, tossing to coat.
Let it simmer for about 5 minutes, allowing the tempeh to absorb the flavors.
Serve immediately, garnished with chopped peanuts and fresh cilantro.