Preheat oven to 425 degrees F.
Rinse sweet potatoes and pat dry. Prick each one all over with a fork. Place sweet potatoes on aluminum foil lined baking sheet and bake for approximately 45-50 minutes. They should be tender and no longer firm.
While potatoes are baking, make the gochujang sauce by combining Kewpie (or mayo) in a small bowl with gochujang and juice of 1 lime. Mix well. Transfer to a resealable sandwich sized plastic bag and store in fridge until time to assemble sweet potatoes.
Approximately 15 minutes before the sweet potatoes are done baking, heat a large cast iron skillet on medium high. Saute SPAM for 5-7 minutes until they have a nice char on them (longer if you want crispier bits). Place on paper towel lined plate and set aside.
In the same pan, give your kimchi a quick saute. You want to get it warm and give it a little char without losing it's crispy texture.
When sweet potatoes are done baking, cut each in half lengthwise. Top the sweet potatoes with kimchi and spam. Snip a tiny corner off of the sandwich bag holding the gochujang sauce and pipe desired amount onto the sweet potatoes.
Garnish with green onions and black sesame seeds (optional).