Cut the peppers into strips about 1.5 cm wide, slice the onion into half-moons, and slice the garlic. If your apaki isn't already sliced, cut it about 5 mm thick.
Heat 1 tbsp olive oil in a 30 cm / 12-inch nonstick or cast-iron skillet over medium heat. Cook the peppers and onion for 8 to 10 minutes, stirring now and then, until the peppers are soft with a few browned spots. Add the garlic for the last minute, then move everything to a bowl.
Wipe the skillet, add the remaining 1 tbsp oil, and heat over medium-high. Fry half the apaki in a single layer for 1.5 to 2 minutes per side, until the edges are browned and slightly curled. Move it to a plate and repeat with the rest. Take the slices off the heat as soon as they brown, because longer cooking makes them dry and tough.
Turn the heat to medium and return the peppers and all the apaki to the skillet. Add the vinegar, oregano and black pepper, and toss for 30 to 60 seconds, until most of the vinegar has cooked off. Taste before adding any salt, since the apaki is already salty. Serve right away with lemon wedges.