For the chicken: Puree the garlic, ginger and yellow onions to a wet paste in a food processor. Rub the paste into the chicken thighs and marinate for at least 12 hours in the refrigerator.
For the relish: Roughly chop the Fresno chiles and parsley and transfer to a food processor along with the garlic and lemon zest. Pulse until the chiles are reduced to small dice. Pulsing, slowly drizzle in enough olive oil to achieve the consistency of a relish. Add lemon juice and salt to taste.
For the garlic confit: Preheat the oven to 250 degrees F. Add the garlic to a small saucepan and cover completely with canola oil. Warm over medium-low heat, then transfer to the oven and cook until the garlic has become very soft but hasn't acquired any color, 30 to 40 minutes. Remove the cloves from the oil, mince and set aside.
For the glaze: Combine the vinegar and sugar in a large pot and stir to blend. Set over high heat and boil until the mixture has reduced to a glaze. Add small amounts of pickled Fresno liquid, garlic confit, lemon juice and salt until the glaze develops a nice, round flavor.
Heat the oil in a deep pot or a deep-fryer to 350 degrees F. Whisk the cornstarch and flour together in a large bowl. Dredge the chicken in the flour and fry in batches until golden brown and cooked through. Drain the chicken of excess oil, then generously brush with the glaze and top with the relish.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.