Kimchi and cheese is one of my favorite flavor combinations! The spicy brininess of the kimchi with the melty gooey cheese is so satisfying and goes great in a grilled cheese, mac and cheese, and of course, on tots.
Place an oven rack in the middle position. Preheat the oven to 450 degrees F.
Pour the neutral oil into a heavy-bottomed pot and bring to 375 degrees F over medium heat. Fry the tots in batches (for a whole bag, 2 to 3 batches) for 6 to 8 minutes each, or until the tots float around and are dark golden and crispy (let them crisp up a bit once they hit the oil before stirring so they don’t fall apart). Be sure to bring the oil back to temperature before adding the next batch. Remove the tots onto a wire rack and cool slightly. Season with salt if needed (some brands of tots are saltier than others).
Transfer the tots to a flame-proof dish that you can also serve in; a 12-inch cast-iron skillet, a nice ceramic baking dish or anything that holds about 3 quarts will work. Evenly top the tots with the chopped kimchi and shredded Cheddar. Bake until the cheese is melted, the kimchi is hot and the edges start to brown, about 10 minutes.
While the tots bake, make the yogurt sauce: Combine the yogurt, soy sauce, toasted sesame oil, lemon juice, kimchi brine and salt in a small or medium bowl. Whisk to combine and set aside. (The yogurt sauce can be made ahead of time and refrigerated; if it separates a little just give a quick stir.)
Turn on the broiler to the highest setting and broil until the cheese is brown and speckly and the edges of the kimchi are browned; start checking after about 3 minutes.
Top the tots with Pickled Onions, yogurt sauce, mayo and scallions. Serve immediately with lemon wedges.
In a small saucepan over medium-high heat, combine the apple cider vinegar, sugar, salt, mustard seed and 1/2 cup water. Bring to a boil and let cook until the sugar and salt are dissolved, Remove from the heat and pour over the onions in a medium bowl. Refrigerate until you are ready to serve. (This can be done ahead of time and refrigerated.)