Preheat oven to 400 degrees and line a baking sheet with parchment paper. Add the sliced plantains to a bowl, add the olive oil and 1 tsp of salt, and toss the plantain slices until they are all coated in the oil.
Place the sliced plantains onto the baking sheet, laying them flat (in one layer) and spacing them out as much as you can. Bake for 10-12 minutes (length of time will depend on thickness) until the plantains are golden and starting to crisp.
Flip the plantains to the other side and cook for up to another 5 minutes or until the chips are golden and crispy. They will burn quickly, so watch closely. When they are done, immediately sprinkle the plantain chips with a little extra salt.
For the guacamole, place the peeled and pitted avocados into a medium bowl. Add the juice of 1 lime and the olive oil. Mash the avocado using a fork or potato masher until it reaches a chunky consistency.
Add the onion, jalapeño, cilantro, and about 1/2-1 tsp of salt. Taste for seasoning and add more salt if necessary.
Serve the plantain chips alongside the guacamole for dipping. Enjoy!