Using a medium to large skillet over medium heat, add the olive oil and onion. Sauté for 3 minutes then add the garlic and sauté for 30 seconds more. 

Add the okra and stewed tomatoes. Stir and let simmer for 15 to 20 minutes, until the okra is tender. You can half over the skillet with a lid to speed up the cooking, just be careful to stir a little more often. 

Once cooked give the okra a taste test to see if you want to add more cajun seasoning or salt and pepper. (I did not add salt because the cajun seasoning has a lot already.) Serve immediately.