1. Wash the lettuce thoroughly under cold running water.
2. Pat the lettuce dry with a clean kitchen towel or paper towels.
3. Remove any wilted or damaged leaves.
4. Hold the head of lettuce in one hand and a sharp knife in the other hand.
5. Starting at the base of the lettuce, make a horizontal cut to remove the core.
6. Cut the lettuce in half lengthwise.
7. Place one half of the lettuce on a cutting board, cut-side down.
8. Starting from the top of the lettuce, make thin slices across the lettuce, stopping just before the bottom.
9. Repeat step 8 with the other half of the lettuce.
10. Use the sliced lettuce to fill your tacos.