In a medium saucepan, warm olive oil over medium heat. Add the diced onion and cook and stir until tender and translucent. Add capsicum and chilli then cook for another 5 minutes until tender.
Add sweetcorn to the saucepan and season with sugar, cumin, salt and pepper. Cook for another 2 minutes, stirring frequently until the sweetcorn is hot through.
Pour into a salad bowl and sprinkle with feta cheese. Serve warm.