Wash your greens really, really well. Best way I've found to do this is to plop them down in your sink, start with a thorough rinse, then pick them over, getting rid of grit and odd stemmy bits. Then shake in table salt and rinse again. The salt seems to help rid the greens of stubborn sand and such. Give a final rinse and blot dry.
The old school method for gumbo greens is to blanch or boil them, but I prefer steaming, which keeps all their lovely nutrients intact. Steam greens in batches -- it may take several batches, but the steaming itself should go quickly, no more than 8 to 10 minutes a pop, so the greens are tender but still vivid green.
Place greens in a colander with a pot beneath to catch all the good veggie broth.
In a large soup pot, make your roux. Pour in 1/3 cup olive oil and heat over very low heat. Whisk in the whole wheat flour so the two form a smooth, thick paste. Continue cooking, whisking occasionally, for a really long time, maybe 45 minutes, or until the roux starts to give off a toasty scent and turns chocolately in color.
Meanwhile, heat remaining 2 tablespoons olive oil in a large skillet over medium heat.
In a food processor, pulse onion and garlic so they're well-chopped, not mushy. Don't have a food processor? Get chopping. Add chopped vegetables to the skillet and stir.
In batches, pulse celery, peppers, and finally, the greens. Add each batch to skillet and stir. Once vegetables start to soften, about 5 to 7 minutes reduce heat to low, cover and continue cooking for another half hour or so, giving the thing an occasional stir.
Your roux and vegetables are now ready to meet each other. Gently stir in vegetable mixture into roux, so everything is well-combined. Bring heat up to medium-high. Add vegetable broth plus any good juices from the drained greens. Add thyme, bay leaf and cayenne. When mixture starts to come to a low boil, cover, reduce heat to medium-low and cook for another hour, stirring occasionally. Oh, don't complain, be generous of spirit. Call a friend, check your e-mail. Pour yourself a glass of wine, if it helps and the church doesn't mind (I won't tell if you won't).
After an hour, you can puree the gumbo with an immersion blender, if you like. Or not.
Splash in the vinegar, season with sea salt and pepper.
Then ladle up and enjoy.