Heat the vegetable oil in a large, wide skillet to 350 degrees F.
Fry the tortillas in the oil until golden brown and crispy, 3 to 5 minutes per side. Remove the tortillas with tongs, shake off any excess oil and transfer to a paper towel-lined baking sheet. Season with kosher salt on both sides.
Add the avocados to a food processor with the sour cream, lime zest and juice and half of the cilantro (stems and leaves). Grate in the garlic and puree until smooth. Season with kosher salt and black pepper. Add 1 tablespoon of the olive oil and pulse several times to combine.
Spread the avocado mixture on the tortillas (about 1/4 cup per tortilla) and top with the red onions, cotija, cherry tomatoes and remaining cilantro leaves. Drizzle with the remaining 1 tablespoon olive oil. Season with flaky sea salt and black pepper.