In a large pot, steam the cauliflower for 5 minutes until tender and translucent white.
Allow cauliflower to cool 10 minutes on the counter or in the fridge.
Meanwhile, chop vegetables – English cucumber, bell peppers, purple onion.
Add English cucumber, bell peppers, purple onion and olives to the pot with cauliflower
In a canning jar or small bowl with a whisk, make Greek dressing. Add Dijon mustard, minced garlic, olive oil, kosher salt, red wine vinegar, lemon juice, dried oregano, dried thyme leaves and shake or whisk together.
Pour dressing over the vegetables and toss to coat.
Crumble half of the feta cheese and toss with vegetables to coat, reserving remaining ¼ cup to crumble when serving.
Cover and refrigerate to marinate and cool for at least 1 hour.
Place into serving dish and crumble fresh feta cheese on top.