Preheat the oven to 425° F. Line a large baking sheet with parchment paper and set aside.
Rinse the fingerling potatoes, as needed, to remove any dirt. Halve the potatoes and add them to a large pot. Add enough water to cover them by an inch or two then bring them to a boil over high heat.
Boil the potatoes for 5 minutes, then drain. Lay the drained potatoes on a clean kitchen towel and allow them to dry out for just a few minutes.
Toss the parboiled potatoes with the avocado oil and salt. Arrange the potatoes cut side down in a single layer on the baking sheet and bake in the preheated oven for 25 minutes.
Flip the potatoes over and return them to the oven for another 10-15 minutes, until crispy and tender.
While the potatoes are roasting, rinse the cilantro and dry it thoroughly. Add it to a food processor along with the scallions, jalapeno, lime zest and juice, garlic, and pepitas. Pulse several times to begin breaking everything down.
Scrape down the sides of the bowl and add the olive oil. Then continue pulsing until you reach your desired consistency.
Serve the crispy potatoes topped with the cilantro sauce. Store leftover sauce in an airtight container in the fridge for up to 3 days.