1. Peel potatoes, and chop into 1-inch pieces. Place in a large saucepan, and cover with cold water. Add garlic, and cook over high heat about 15 minutes or until potatoes are easily pierced with a fork.
2. While potatoes cook, tear bread into 3 or 4 pieces and place in a large bowl. Spoon 2 to 3 tablespoons cooking liquid from potatoes over bread. Stir with a fork until smooth. Add yogurt, 2 tablespoons olive oil, and zest and juice of 1 lemon; stir until a smooth paste forms.
3. When the potatoes are done, place a large bowl in the sink and set a colander on top. Drain potatoes and garlic, reserving cooking liquid. Transfer potatoes to bread mixture and mash until smooth (a potato ricer works well for this task). Add reserved cooking liquid 2 tablespoons at a time until mixture takes on the consistency of loose mashed potatoes. Stir in ï¿½ teaspoon salt and 2 teaspoons olive oil. Cover and keep warm until ready to serve.
4. Preheat grill pan over medium-high heat. Drizzle fish with ï¿½ teaspoon olive oil and season with remaining ï¿½ teaspoon salt and thyme. Cook fish 2 to 3 minutes on each side until fish flakes when tested with a fork or until desired degree of doneness. Transfer to a plate; cover and keep warm until ready to serve.
5. Place bell pepper, zucchini, and red onion in a large bowl. Drizzle with remaining ï¿½ teaspoon olive oil; toss to coat. Arrange bell pepper in grill pan and cook 5 minutes over medium heat. Add zucchini and onion; cook 10 minutes or until vegetables are tender, turning as necessary to ensure even cooking.