Heat 2 tablespoons of olive oil in a large skillet over medium-high heat.
Add the cauliflower florets in a single layer and let cook for a few minutes, undisturbed, until browned.
Using tongs, flip the florets over and allow them to brown on the other side.
Remove the cauliflower from the skillet and place on a plate and set aside. Allow the skillet to cool for a few minutes.
Using the same skillet, heat the remaining tablespoon of olive oil over medium heat. Add the garlic and saute for about 30 seconds.
Add the can of tomatoes with the juice and the crushed red pepper flakes. Use a wooden spoon to break up the tomatoes as they start to simmer.
Add the olives and capers and allow the sauce to simmer about 10 minutes, stirring occasionally.
Return the cauliflower florets to the skillet and carefully toss with the sauce. Simmer for about 15 minutes more until the cauliflower is tender and the sauce has thickened. Add the fresh oregano and season to taste with salt and pepper. Serve immediately.
Notes
Leftovers can be refrigerated in an airtight container for 3 to 4 days.