Scrub the potatoes under running water and use a small knife to slice away any little sprouts (but don't peel any further).
Add the potatoes to a large saucepan or big pot and completely cover with room temperature water. Add 2 tablespoons of fine sea salt. Bring to a boil and then slightly lower the heat to a vigorous simmer. Cook for 12-15 minutes, depending on the size of your potatoes, until fork-tender. Drain the potatoes.
While the potatoes simmer, heat the oven to 425°.
Pour 1 tablespoon of avocado oil on a baking sheet and brush it around to cover the sheet. Add your potatoes, giving them enough room between each other to spread out when you smash them. Using another baking sheet, spatula or bottom of a drinking glass, smash the potatoes until about ½-inch thick.
Brush the potatoes with 2-3 tablespoons oil. They should be thinly but evenly coated. Too much oil and they'll be soggy; too little and they'll be dry.
Bake for 30-35 minutes, until the edges are brown and crispy. Remove from the oven, sprinkle with a little more sea salt and freshly ground black pepper and let cool slightly.
Cook the bacon to desired crispness while potatoes are baking, then drain and chop.
Use a thin spatula to remove them to a serving plate (they'll fall apart a little, depending on how thinly you smashed them). Top them with the ranch dressing, crumbled bacon and chives (if using).