By Sarah Murphy-Kangas, In Praise of Leftovers
1. Thinly slice 1/4 head of green cabbage and several large washed, ribbed Swiss chard leaves.
2. Toss them with very thinly sliced red onion, a glug of olive oil, coarse salt, a dash of white wine vinegar, and some crushed red pepper, if you like.
3. Smash avocado (or lay sliced avocado) on your tostada shell and top with slaw.