Claypot Fish and Potatoes

Name: Claypot Fish and Potatoes
Ingredients: 3 Yukon potatoes, sliced into 1/4-inch slices; Salt and freshly ground pepper; 1/4 cup olive oil, plus extra for greasing dish and brushing on lemons; 3/4 pound white fish fillets, such as cod, flounder or tilapia; 4 cloves garlic, minced; 2 teaspoons minced fresh thyme; 1/2 lemon, juiced; 1 yellow onion, sliced; 3 Roma tomatoes, thickly sliced; 1/2 cup good quality black olives, pitted and lightly crushed and sliced in half; 1 lemon, quartered; Special Equipment: 15 1/2-by-7 1/2-inch terracotta cazuela (baking dish)