Remove excess fat from lamb fillet and cut into approximately 1 cm thick slices. Marinate the lamb with olive oil, pressed garlic, finely chopped sage leaves, salt, and pepper. Refrigerate for 1 hour.
While lamb marinates, prepare vegetables: Remove stems and seeds from bell peppers and cut into large pieces. Peel carrots and cut into thin slices. Peel onion and cut into very large pieces.
Cook potatoes with or without the skin on in boiling water on medium-high heat until fork-tender, roughly 15-20 minutes. Drain and cool completely, then cut into very large pieces.
Heat a small amount of olive oil in a large saucepan on medium heat. Add garlic and carrot slices, cook for 2-3 minutes. Add bell pepper pieces and onion pieces, cook for 5-7 minutes until vegetables are tender but still firm. Add potato pieces and cook for 2-3 minutes. Season with salt and pepper. Set aside and keep warm.
Remove lamb slices from the marinade and pat dry with paper towels. Heat a small amount of olive oil in a pan on medium-high heat. Add bay leaves and lamb slices, searing for roughly 3-4 minutes per side until browned. Cover the pan, reduce heat to low, and keep warm at approximately 80-100°C (176-212°F). Blot any excess fat with paper towels.
Make the sauce: Pour balsamic vinegar into a saucepan and bring to a boil on medium-high heat. Reduce for roughly 5-7 minutes until syrupy with only a small amount of liquid remaining. Add broth and return to a boil, cooking for 5 minutes. Reduce heat to medium-low, stir in honey, and simmer for another 5-7 minutes. Season with salt and pepper to taste.
The Boss Kitchen editorial staff oversees content review, fact-checking, and recipe verification across the site. Published articles pass through the editorial team before going live, ensuring ingredient lists, techniques, cooking times, and nutritional claims hold up in a home kitchen. The team coordinates contributions across the site writers, handles reader corrections, and maintains consistency in measurement conventions, safety guidance, and dietary labeling. Posts under this byline typically represent team-reviewed reference material, site announcements, or editorial roundups rather than individual-author features, and they are held to the same sourcing standards as bylined recipe and product coverage.