Step 1:
Using a large bowl, mix oil, vinegar, mustard, thyme, rosemary, bay leaves, smashed garlic, and honey together. Add meat and mix once more. Cover with plastic wrap and put in the refrigerator for 1 hour.
Step 2:
Preheat oven to 230°C. Take the roast out, and pat dry with a paper towel. Season generously with salt, pepper, rosemary, and minced garlic. Put the meat into the oven.
Step 3:
Roast till preferred 'done-ness'. Let it rest for 10 minutes.
Step 4:
For the sauce, use a medium-sized bowl. Mix yogurt, sour cream, horseradish, and lemon juice. Then season with salt.
Step 5:
Slice the tenderloin to servable portions with sauce as a side.