Heat oil in a large stockpot on med-high heat and saute garlic.
Add in cabbage, bell peppers, onion, and carrots. Season with red pepper flakes and pepper, to taste. Simmer on med heat for 20-30 minutes, until cabbage is softened and cooked down, stirring occasionally.
Add in spinach leaves; simmer for 5-10 minutes, stirring occasionally, until spinach wilts.