Set your comal over the flame and let it get properly hot before you put anything on it — no oil, nothing. Lay the tomatillos and the serrano chiles directly on the dry surface and leave them alone for a minute or two before you turn them. You want real char, real blisters, the skin pulling away and darkening. The tomatillos will take four or five minutes, the chiles a little less. When they soften and smell like they have been kissed by fire, they are ready. Into the blender they go — still hot — with the quarter onion, the garlic, a good handful of cilantro, and salt. Blend it until it is smooth and thick, not watery. Taste it. It should have brightness and a little bite. If it needs salt, add salt.

Now cut your tortillas into strips, wide as two fingers. Yesterday's tortillas are the right tortillas for this — they have dried a little, they have character, they will not turn to mush in the pan. If yours are too fresh and soft, lay them out and give them an hour of air before you start. This is not a step most recipes will tell you, but it matters.

Put your lard in a wide skillet — enough to coat the bottom well — and bring it up over medium-high heat until it is shimmering and alive. Add the tortilla strips and do not walk away. Stir them, move them, let each piece find the heat. You are looking for soft with a little gold at the edges, three or four minutes. They should bend when you press them, not snap. Not too crisp, not too pale. If your pan is small, do this in two rounds — a crowded pan steams instead of fries and that is not what we want.

Pour the salsa verde over the tortillas and stir everything together so every strip is coated. Let it all simmer quietly for a minute or two — this is when the tortillas begin to drink in the sauce and the whole pan becomes one thing instead of two. The sauce should cling to the tortillas, not pool at the bottom of the pan. If it is too thick, add a small splash of water and stir. If it looks right, leave it.

Push the tortillas to the sides a little and crack your eggs into the centre of the pan. Let them sit just a moment, then take your wooden spoon and begin to fold them slowly into the tortillas, breaking them into soft, lazy curds as they set. Two or three minutes is all they need. You want the eggs just cooked, still tender, folded through everything like they belong there — because they do. Taste for salt before you take the pan off the heat.

Serve it on a warm plate immediately — this dish does not wait and does not improve from sitting. Scatter a few fresh cilantro leaves on top and some thin rings of raw white onion. That is how I do it. Some cooks will bring crema or a wedge of lime to the table, and I will not argue with them. But the verde is the thing — if you made it right, it does not need help.