Steak Sandwiches with Fennel Slaw

Ingredients

• 1 chilled leftover steak (from Pan-Roasted Steak with Crispy Broccoli)
• 1 small fennel bulb, very thinly sliced, plus coarsely torn fronds
• 1/2 small red onion, very thinly sliced, rinsed
• 1/4 cup leftover cilantro salsa verde (from Pan-Roasted Steak with Crispy Broccoli)
• 1/2 tsp. kosher salt, plus more
• Freshly ground black pepper
• 1 sandwich-size piece focaccia, split lengthwise, toasted
• 4 Tbsp. mayonnaise

Directions

1. Slice steak against the grain into as-thin-as-you-can-get-them strips (this is much easier to do when the steak is cold). Transfer to a large bowl and let sit at room temperature while you make the slaw. If you have time, slice the steak before you start cooking; an hour is ideal to completely take off the chill.
2. Toss sliced fennel, red onion, salsa verde, 1/2 tsp. salt, and 1 Tbsp. fennel fronds in a large bowl to combine. Season slaw with a few grinds of pepper and toss again.
3. Spread cut sides of focaccia with 2 Tbsp. mayonnaise each; transfer to plates. Divide steak between bread and crown each sandwich with a big handful of slaw. (You may have a small amount left—nibble on it or serve on the side.) Top sandwiches with more fennel fronds and sprinkle with salt.