Preheat oven to 450 degrees F.

Place potatoes in a large pot and cover with cold water by 1 inch; season with salt.

Bring to a boil and cook over medium-high heat until just tender, about 7 minutes; drain.

Meanwhile, pulse sourdough bread in a food processor to make coarse crumbs.

In a large bowl, combine breadcrumbs with olive oil, grated garlic, lemon zest, 1 teaspoon salt and a few grinds of pepper.

Add the potatoes to the breadcrumb mixture and toss to coat.

Arrange potatoes cut-side down on a baking sheet.

Roast for 10 minutes, or until golden and tender.

Sprinkle with parsley and parmesan cheese.

Continue roasting for 5 more minutes, or until golden brown.

Transfer to a serving dish and season with salt to taste.

Serve immediately with lemon wedges.