Using a 2 inch circular punch, cut 4 circles out of white corn tortillas.
Heat oil in a skillet over medium-high heat. Fry the tortilla circles in peanut oil until golden brown and crispy. Drain on paper towels. Add thinly sliced garlic to the oil and cook until golden and crispy. Drain.
In a bowl mix yuzu juice, fish sauce and sesame oil together. This is the ponzu sauce.
Thinly slice the hamachi into 1 1/2-inch square slices, about 1/4 inch thick. Marinate the hamachi in the ponzu juice for about a minute.
Place hamachi slice onto mini-tostada, then layer with cilantro leaf, crispy garlic, shaved serrano, onion and bacon.