In a large saucepan, bring 3 cups water, the bulgur and 1/2 teaspoon salt to a boil; lower the heat, cover and simmer until tender, 10 to 12 minutes; transfer to a bowl. Toss with 3 tablespoons olive oil, the finely chopped onion, parsley, chopped oregano and lemon juice. Season with salt and pepper and refrigerate until ready to serve.