Slice sourdough bread into thick slices (1 per person) and brown in toaster.
Spread generous amount of Duke's mayonnaise on each slice.
In cast iron skillet, melt butter over medium heat.
Warm up (but do not overcook) leftover picanha steak slices.
Layer warm picanha on slices of mayo covered bread.
Spread leftover chimichurri sauce on the picanha steak.
Chop cherry tomatoes in quarters, sprinkle over each open face sandwich.
Garnish with fresh blue cheese crumbles.
Serve and enjoy!