01 -
Mix the softened butter with crushed garlic and diced dill until well combined. Set aside.
02 -
For easier slicing, freeze steak briefly, then slice into thin strips.
03 -
Heat oil in skillet over high heat. Add beef strips, season generously with salt, and cook until just golden. Remove and set aside.
04 -
In the same skillet, sauté onion half-rings until golden brown. Remove from heat.
05 -
Split baguette lengthwise and spread herb butter on both sides. Layer with steak, caramelized onions, and Havarti cheese slices.
06 -
Keep sandwich open-faced and broil for about 2 minutes until cheese gets bubbly and melts. Serve immediately while hot.