Heat lard or butter in a medium pot over medium heat. Add sliced garlic and sauté for 30 seconds until fragrant (but not browned).
Add diced potatoes, broth, marjoram, bay leaf, salt, and pepper. Bring to a boil.
Lower heat and simmer covered for about 12–15 minutes, or until the potatoes are fork-tender.
Meanwhile, make the croutons: fry the cubed rye bread in lard or oil until crispy and golden. Drain on paper towels and lightly salt.
Taste the soup, remove bay leaf, and adjust seasoning if needed.
Serve hot, topped with crispy croutons and a sprinkle of cheese or parsley if you like!
