Matambre - Argentine Rolled, Stuffed Flank Steak

INGREDIENTS

• 2 (2 lb) flank steaks
• 1/2 cup red wine vinegar
• 1 teaspoon finely chopped garlic
• 1 teaspoon dried thyme
• 3 cups beef stock
• 1 -3 cup cold water
• 1/2 lb fresh spinach, washed, drained, and trimmed of stems
• 8 carrots, scraped, cooked, 6 to 8 inches long
• 4 hard-boiled eggs, cut into quarters lengthwise
• 1 large onion, sliced into rings
• 1/4 cup fresh parsley, finely chopped
• ground black pepper (to taste)
• 1 tablespoon coarse salt