Finely chop 1 medium onion. Heat 1 tablespoon oil in a non-stick pan over medium heat and cook the onion for about 5 minutes until golden brown. Soak 1 stale bread roll in water for about 2 minutes, then squeeze out excess water. In a large bowl, combine 400 g minced meat, the roasted onion, squeezed bread, 1 egg, 2 teaspoons salt, pepper to taste, 1 teaspoon dried marjoram, and 1 chopped garlic clove. Mix well by hand. Cover and refrigerate until ready to use.
Heat 3 tablespoons oil in the same pan over medium heat. Form small balls from the meat mixture and brown them for about 15 minutes, stirring occasionally, until cooked through (internal temperature 63°C / 145°F). Transfer meatballs to a plate and set aside.
While the meatballs are cooking, peel, wash, and slice 400 g carrots. After the meatballs are removed from the pan, add the carrot slices to the remaining oil and roast for about 5 minutes until lightly browned. Pour in 250 ml broth to deglaze the pan, scraping up any browned bits. Season with salt and pepper to taste. Stir in 3 teaspoons curry powder and 1 teaspoon lemon juice. Add 3 tablespoons crème fraîche and stir well. Reduce heat to low and cook for about 5 minutes until sauce reaches desired consistency. Return the meatballs to the sauce and cook for 3 minutes.