Peel and chop 3 large russet potatoes into smaller chunks so they cook faster. Add them to a pot of salted water and boil until they’re fork tender, or until the internal temp hits about 205°F.
Drain well and transfer to a large bowl.
Season the potatoes generously with salt and pepper, then mash them as smooth as possible. The goal is no chunks and for a soft and fluffy inside.
Add ¼ cup cornstarch to the mashed potatoes and mix well until fully combined. This gives it structure so the potato doesn't melt into the oil when frying.
Use a 1 ounce scooper to portion the potato mixture into balls (this makes about 30 balls).
Heat neutral oil in a pot to 350°F.
Fry the potato balls in batches until golden brown and crispy, about 3–5 minutes. Don’t overcrowd the pot or the oil temp will drop and you’ll lose the crunch.
Drain on a rack or paper towels.
While the potatoes fry, melt 1 stick of butter in a small saucepan.
Stir in anchovy paste (or mashed canned anchovies) until it dissolves into the butter.
Transfer the fried potato balls into a large bowl and pour in a generous amount of the anchovy umami butter, then sprinkle Maika‘i Furikake all over.
Toss until everything is glossy and coated.
Serve hot.