(*Chef's note: To prepare Brussels sprouts, trim ¼ inch from the bottom and score the trimmed sprouts with a deep X.) In a large saucepan, cover the potatoes with water; bring to a boil over high heat and cook for 5 to 8 minutes, or until fork tender.
Add the Brussels sprouts and cook for 5 minutes, or until fork tender.
Drain, reserving ½ cup of the cooking liquid.
In a large nonstick frying pan at medium-high heat, sauté the garlic in the oil for 3 minutes, or until it is just beginning to color.
Add potatoes, Brussels sprouts, ¼ cup of the reserved cooking liquid, and oregano; add salt substitute and pepper to taste.
Cover and heat through, adding more liquid as needed.