Add oil to a frying skillet (should be about 1.5 inches of oil), and heat over medium heat.
Place egg into a shallow bowl, set aside. Set panko and red pepper flakes into a different shallow bowl, mix to combine, set aside. Dip each tender into egg, then coat with panko breadcrumbs. Set aside.
Place tenders into heated oil in the frying skillet. Don't overcrowd the skillet, cook in batches (I did 4-5 each batch). Fry for 3-4 minutes on the first side, when browned flip to other side, cook 2-3 minutes or until browned. Remove from skillet and set on a paper towel lined plate. Repeat for all tenders.
To make the sauce: Add garlic, brown sugar, soy sauce, sriracha, peanut butter, ginger, water, and cornstarch to a small sauce pot. Whisk to combine completely. Heat over medium high heat and bring to a boil, whisking occasionally. Reduce heat to a simmer and let sauce thicken (should only take a minute or 2). If sauce seems too thick, you can add a bit more water to thin it.
Carefully take each tender and dip into the sauce, coating completely. Repeat for all tenders. Serve immediately garnished with chopped cilantro.