How to Make It
Cook the potatoes in a large saucepan of salted boiling water until just tender, about 20 minutes. Drain and cool; halve the potatoes.
Light a grill. In a large bowl, toss the potatoes and onions with the 1/2 cup of olive oil and season with salt and pepper. Grill over moderate heat, turning, until the onions are tender and the potatoes are golden and crispy, about 3 minutes for the onions and 10 minutes for the potatoes. Transfer the onions and potatoes to a platter and season with salt, pepper and oregano. Top with the pickled chiles and drizzle with olive oil and the brine. Garnish with chopped parsley and serve warm.