Fill a medium pot halfway with cold water. Stir in the tablespoon fine sea salt.
Peel potatoes and cut into 1-inch pieces, adding to the pot as you go.
Bring water to a boil, then reduce heat to simmer, uncovered, until potatoes are tender, about 10 minutes.
Scoop out and reserve 1 cup of cooking water, then drain potatoes and return to pot.
Meanwhile, peel garlic, smash cloves with the side of a chef’s knife, and mince.
In a small pot over medium-low heat, simmer garlic in olive oil for a few minutes without browning.
Off the heat, stir wasabi paste into oil.
Mash potatoes until smooth.
Pour in garlic wasabi olive oil, along with some of the reserved cooking water to loosen the consistency to your liking. Stir until creamy.
Taste and adjust for salt and wasabi.
