Rinse the cilantro with water and pat with a paper towel to remove the excess water. Let it sit on the paper towel to drain.
Chop the tomato into ¼ to ½-inch thick pieces (makes about 3 cups). Add it to the bowl.
Chop the onion into ¼-thick pieces (makes about ½ cup). Add it to the bowl.
Remove the cilantro leaves from the stems and finely chop the leaves until you have ⅓ to ½ cup. Add it to the bowl and stir everything together well.
Chop the avocado into ¼ to ½-inch thick pieces. Add it to the bowl.
Cut the lime into 4 wedges and squeeze 2 wedges into the bowl. Add the salt. Lightly stir the pico together and taste. Add more lime and salt as desired.