Preheat oven to 450 F.
Cut a head of cauliflower into slices about 3/4 inches thick.
Place cauliflower slices in a single layer on a roasting pan. Be sure that there is good space between them.
Drizzle both sides of the cauliflower with olive oil and season with salt and fresh ground black pepper. Use a fair amount of pepper, but hold back a wee bit on the salt since the olives are salty.
Roast cauliflower in oven for a total of 25 – 30 minutes, turning after the first 15 minutes. Roast until it is the way you like it.
While the cauliflower roasts, mash 1/2 tsp. minced garlic with some salt.
Dice up 1/4 cup Kalamata olives into fairly small pieces.
Add about 2 Tablespoons lemon juice to the garlic/salt, then whisk in 2 Tablespoons olive oil, whisking until the vinaigrette is emulsified. (Try other acids as well. I used a champagne vinegar. The amount of acid should be adjusted based on your personal taste.)
Then mix in the chopped olives and let dressing sit so the flavors blend while the cauliflower finishes roasting.
When the cauliflower is done roasting, you may trim out the core section of the cauliflower (or leave it – your preference) and place on serving dish. Spoon the olive/garlic vinaigrette over the cauliflower pieces and serve hot.