Slice the avocados in half lengthwise, remove the pit, and scoop the flesh into a mixing bowl. Mash to desired consistency.

Finely dice the onion and chop the tomato. If using, mince the jalapeño. Fold these ingredients into the mashed avocado.

Squeeze in the lime juice over the mixture. Season with salt to taste.

Taste the guacamole and adjust lime juice and salt as needed.

Transfer to a serving bowl and garnish with diced tomatoes or cilantro. Serve immediately.