With a fork, mix the lime juice and olive oil in a small bowl or glass and then set aside.
Remove the heavy stem bases of the cilantro. Chop the remaining leaves and thin stems as fine as you can without trying particularly hard. (You wouldn’t want any stress to make its way into the dish.)
Remove the stem of the chile. If you’d like to make sure the pico de gallo isn’t very spicy, also slice the chile lengthwise and remove the seeds, ribs, and pith. (Be sure not to touch your eyes afterward or it will burn!) After the chile is stemmed and optionally de-ribbed and seeded, cut it into a very fine dice.
Cut the onion and tomatoes into pieces 1⁄3 inch per side or less; I think 1⁄4 inch per side is ideal.
Put the tomatoes, onion, and chile in a large bowl and toss them together, seasoning with salt and pepper. Add the lime juice mixture and toss a little more. Use immediately or keep in the fridge for up to 1 week.
Pico de gallo https://thetasteedit.com/baja-beer-battered-fish-tacos-with-cabbage-and-white-sauce/