Preheat the oven to 425 degrees F (220 degrees C). Spray a sheet pan with vegetable spray and set aside.
Prepare the Jerusalem Artichoke (0.5 pound) first. Add the Lemon (1) into a medium bowl and add the Water (1 cup). Peel the artichokes with a vegetable peeler and cut into bite-sized pieces. Immediately transfer to the water.
Place White Potato (0.5 pound), Brussels Sprouts (0.5 pound), Carrot (0.5 pound), and Onion (1) to the sheet pan.
In a small bowl combine the Garlic (1 clove), Fresh Rosemary (1 teaspoon), Kosher Salt (3/4 teaspoon), and Ground Black Pepper (1/2 teaspoon). Remove the artichokes from the water and pat dry with a clean towel. Add them to the other vegetables.
Drizzle the vegetables with Olive Oil (3 tablespoon) and sprinkle on the rosemary mixture. Use your hands to to coat the vegetables with olive oil and herb mix.
When they are coated, arrange the vegetables so that the cut side of the brussels sprouts and potatoes are on the cookie sheet. Spread the rest of the vegetables out in an even layer.
Roast for 25 to 30 minutes, then use a metal spatula to flip the vegetables over.
Continue roasting for another 10 to 15 minutes or until golden brown and fragrant.
Transfer to a serving dish and serve warm!