Poblano chiles well roasted on a BBQ grill. Make sure they're completely black from the roasting.
Peel 'em.
Here's the trick. Put 'em in a plastic bag for around half an hour before you peel them. That'll help loosen the skins and make it easier to peel.
Now cut the chili lengthwise, and remove the seeds. Make sure you get them all.
Rinse the chiles with cold water. You'll end up with what looks like a bunch of skinned lizards
Roll them in flour
Cut panela cheese into thin strips the length of the chiles, and stuff the chiles with them. Don't overstuff or you'll end up with exploded relleno, and that's no good
Get some eggs, one per chili, and separate them. Beat the whites until stiff. Beat the yolks a little bit and fold them into the whites. don't beat them together like some people do - that's scrambled eggs. You have to remove the protein yolk in order for the egg whites to stiffen.
Get a big frying pan (cast iron is best), and put a good bit of oil in it. Get it HOT. Dip the chiles in the egg batter - make sure they're completely and pretty thickly covered. Then fry 'em up in the pan. If you did it right, the batter will expand and will look like a giant golden brown elephant ear. Now put 'em in a warm oven for 10 minutes or so to melt the cheese.
Some people then dip 'em in tomato sauce, but I call that wrong. They should be eaten plain - the tomato will hide the taste of the roasted chili and that should be illegal.