Step 1Combine cauliflower, 3 tablespoons olive oil and salt and pepper to taste in medium roasting pan. Mix well to coat all of cauliflower pieces. Roast at 425 degrees 15 minutes. Add garlic and mix well. Continue to roast until cauliflower is tender yet still slightly crisp, about 8 to 10 minutes.
Step 2While cauliflower is cooking, place mustard in small bowl. Add anchovies and mash with fork, combining with mustard. Stir in vinegar. Combine 1/2 cup olive oil and vegetable oil and pour slowly into bowl while whisking constantly.
Step 3Transfer cooked cauliflower to large bowl and toss with about 1/2 cup vinaigrette while cauliflower is still warm. Mix in capers and parsley. Serve salad at room temperature, not chilled.