Romaine Lettuce (AKA Cos Lettuce) is frequently Infested with insects and must be checked.
How to check Romaine Lettuce
1. Remove each leaf from the head.
2. Soak the leaves in a solution of dishwashing liquid and water. Allow to soak for at least three minutes. Agitate the leaves in the solution.
3. Remove the leaves from the solution.
4. Direct a stream of water at each leaf, on both sides, making sure that every spot is covered. One should be especially careful to cover every fold and corner.
5. To see if this process worked, take about ten per cent of the leaves and check them.
If no infestation is found, the remaining leaves may be eaten after being washed thoroughly. No further checking is necessary.
6. Even one insect being found is an indication that the soaking and washing were not effective. In such a case, all leaves need to be soaked and washed again. (Follow steps 1-5.)
If infestation is found after the second soaking and washing, steps 1-5 may be repeated again. If infestation is found after the third soaking and washing, one should either discard the produce or check every piece.