The biggest thing that helped dd with letter recognition was duplo blocks with letters. We 'play blocks' as a family activity here, and to have letters incorporated into a game seamlessly meant it was always there, but not a 'lesson' iykwim? I have never done flash cards, but my dd is stubborn and I can imagine her refusing to participate.

Do you have magnet letters on the fridge, an alphabet poster in her room etc? What about an alphabet puzzle?

I found incidental learning works best for my kids at this age anyway.