Best homestyle, grandmotherly Mexican I currently know in the Tristate area:
257 Battle Ave
White Plains, NY
It's next door to Ruth's Jamaican (which is known and very good), and about 1/2 mile up the hill from Central Avenue circa the new H Mart. You can be there in 5 minutes off of Rt. 287 (take exit 5, and hang a right at City Limits Diner, which has been slipping).
It's just another humble Mexican deli with steam table. But it's not marginally better, it's off the scale. Not in a "fabulous" way. No clever regional cooking, no impressive ingredient sourcing. Just staunchly authentic (not an iota of gringo pandering) and exceptionally delicious. this is how your Mexican grandma cooks you lunch...if she's a particularly talented Mexican grandma.
I've had a bunch of things. Even the tortillas - crummy store bought, but heated to order on a hot seasoned grill and brought to your table with radiant delight - have tons of je ne sais quoi.
Today I had ribs in a brown sauce that was bewitchingly complex and soulful. Rib meat was awesomely tender, and every bit of possible flavor was extracted. Chicharrones with calabasa (pig skin stewed with squash) was every bit as homey/soulful as it sounds. Carnitas are exactly like Mexico. Everywhere else, it's just cooked meat, spiced up hastily. Here, it's knuckles of pork, good-chewy, and so loaded with flavor you can't keep your eyes open.
Rice is moist and you can't get enough of it (that alone stands this place out; I can count on one hand the Mexican places with truly great rice). Homemade horchata is just perfect. Just like Mexico, but better than that - it's just like a GOOD place in Mexico, much more grandmotherly than the usual.
Staff is guarded but open up with effort (they like compliments on their cooking).
Customers are a step up in eating intensity from the usual blase Hispanic worker dudes. I get the feeling they travel an extra few miles to come here. Not crowded yet, though.