Step 1Preheat the oven to 150 °C/ 300 °F (fan assisted), or 170 °C/ 340 °F (conventional). Peel the garlic and slice it into smaller pieces. Black garlic is aged white garlic and you can find it in most large grocery stores. It's sweet and has similar taste like balsamic vinegar. If you can't find black garlic, use freshly sliced white garlic.