Whisk oil, lime juice, shallot, and serrano pepper until well mixed. Stir in salt and pepper to taste and set aside.
Heat a large skillet over medium and once hot, fry the bacon until brown and crispy. Use a slotted spoon to remove the cooked bacon from the pan and let cool on a clean, cloth towel.
Slice the honeydew in half and scrape out the seeds with a spoon. Using a melon baller, press down firmly into the honeydew and twist to scoop out melon balls. Place the melon balls into a bowl and continue until you’ve scooped out the whole honeydew. Note: Stop here if making ahead of time and place ingredients in the fridge until ready to continue.
Slice the avocados lengthwise and remove the pit. Using the melon baller, with a little less pressure, twist and scoop the avocado from their skins. Place the avocado balls in a separate bowl from the melon.
Pour the serrano shallot mixture through a mesh strainer to separate it from the vinaigrette. If you prefer more heat you can leave some of the serrano pepper mixture in the vinaigrette.
Toss the honeydew with the cooled bacon pieces and strained lime-serrano vinaigrette. Fold in the avocado carefully, so that it does not break apart. Place in a large bowl or platter and serve immediately.