Slice the cucumbers open lengthwise, then place cucumbers flesh side down and smash the cucumber halves with the flat side of a large knife (similar to how you would smash garlic cloves!); the cucumber will split open. Cut at a 45 degree angle into 1-inch pieces and transfer to a large bowl, then add in avocado chunks, scallions, lime juice, cilantro, jalapeño, and salt. Gently toss with a large spoon to combine. Taste and add more salt, if necessary. Cover and place in the fridge until ready to serve.