Husk and rinse the tomatillos to remove their sticky residue, then quarter and toss them with a tablespoon of olive oil or avocado oil and a pinch of salt on a baking sheet. Roast at 425° for about 15 minutes, until soft and lightly browned.
Transfer the roasted tomatillos and their juices to a food processor and blend until mostly smooth, with some texture remaining. Season to taste.
Meanwhile, halve the poblanos lengthwise, remove the seeds and ribs, and brush them lightly with oil. Season with salt and roast skin-side down on a baking sheet for 15 minutes at 425°, until the skins blister.
Once cool enough to handle, peel the skin from the peppers, then dice.
In a large skillet, heat a tablespoon of oil over medium heat. Add the onion and a pinch of salt and cook until the onions are soft and translucent, about 5 minutes.
Stir in the garlic and cook until fragrant, 1 to 2 minutes more.
Add the spinach and another pinch of salt, cooking just until wilted but still bright green.
Stir in the diced poblanos, coriander and cumin, then pour in the tomatillo puree and simmer over low heat for 5 minutes. Taste and adjust seasoning.
Make small wells in the sauce and gently crack the eggs into each one. Cover and cook over low heat until the egg whites are set and yolks are still runny, 5 to 7 minutes.
Top with chopped cilantro, jalapeño slices, and avocado just before serving.