To make chicken marinade, process 1 tsp salt, paprika, garlic, chillies, 2 tbs oregano, vinegar and 80ml (1/3 cup) oil in a food processor until smooth. Toss with chicken in a large bowl to coat. Refrigerate for 1 hour to marinate.
Meanwhile, place potatoes in a pan of cold water, bring to the boil and cook for 15 minutes or until just tender. Drain. Cool, then thinly slice.
Heat a chargrill pan or barbecue to medium. Brush corn with 1 tbs oil, then cook, turning, for 8 minutes or until lightly charred and tender. Cool. Cut corn kernels from cobs, keeping them together in large chunks.
Meanwhile, in the same pan, cook capsicum, turning, for 8 minutes or until skin is blackened. Place in a bowl, cover and leave for 8 minutes, then rub off skin. Carefully cut flesh into thin strips (juices will be hot). Discard seeds.
Increase heat to high. Thread 2 pieces of chicken onto each skewer. Cook the skewers, in 2 batches, for 4 minutes each side or until cooked through.
Whisk lemon juice, cumin, parsley, remaining 1 tbs oregano and 60ml (1/4 cup) oil in a large bowl. Season with salt and pepper. Add potatoes, corn and capsicum, and toss to combine.