Make the ginger dressing: In a small food processor or spice grinder, purée the pickled ginger with the pickling liquid. Transfer to a medium bowl and whisk in the soy sauce, sugar, lime juice, and salt. While whisking continuously, drizzle in the oil to form an emulsion. Add the fresh ginger and set aside.

Make the serrano emulsion: Roast the serranos on a stovetop open flame, using tongs to rotate occasionally, until charred and blistered all over, about 5 minutes. Transfer to a medium bowl and cover with a lid or plastic wrap. Set aside to steam until the chile skins loosen, 5–10 minutes.

Using a paper towel, rub the skins off the serranos. Slice the chiles in half, discard the stems and seeds, then transfer to a blender. Add 1–2 tablespoons of water and process until smooth, 1–2 minutes. Add the egg yolks and 1½ teaspoons of the lime juice and continue blending to combine. With the blender running on medium-high, drizzle in the oil to form an emulsion. Blend in the salt, sugar, and the remaining lime juice, then set the mixture aside.

Make the beef kachila: In a medium bowl, stir together the beef, onion, cilantro, cumin, chile powder, ginger, serrano, and 2 tablespoons of the reserved ginger dressing. Season to taste with salt, then transfer to the fridge while you roast the shishitos.

Roast the shishitos in a dry cast iron skillet over medium-high heat or directly over an open stovetop flame, using tongs to rotate the peppers frequently, until lightly blistered all over, about 2 minutes. Transfer immediately to a small bowl and set aside until cool enough to handle.

Using the tip of a paring knife, make a slit lengthwise down one side of each shishito, then transfer them to the bowl with the remaining ginger dressing. Toss to coat the peppers in the dressing, then set aside to marinate at room temperature for 15 minutes.

Drain the shishitos, discarding the ginger dressing or reserving for another use. Arrange the shishitos cut-side up on a serving platter. Using either a piping bag or a small spoon, fill the peppers with the kachila. Top each with a thin line of serrano emulsion and a dollop of the caviar, garnish with fried shallots, parmesan, and edible flower petals if desired, and serve at room temperature.