Preheat oven to 425° + place naan on a sheet pan; bake 5-7 min

Meanwhile heat lightly oiled skillet over med-high; pat meat dry, season with salt/pep + sear 2-3 min undisturbed until browned; flip meat over + sear 2-3 min more for medium-rare (for more well done, increase cook time 1-2 min per side); set aside to rest a few min, then slice into bite sized pieces

Spread 2-4 tbsp curry onto flatbread + layer on beef, followed by 2 handfuls of spinach; slice naan flatbread in half + add to plates