Well you did say "lower" Westchester, so I'll chime in with Little Mexican Cafe on Main St. in NewRo. I only eat fish and they have a red snapper special that can be amazing with your choice of red or green sauce -- and they'll make it as hot as you like, even too hot. Prices seem to vary on the fish each time, so ask. El Tio across from New Roc City actually has more refined Mexican food than LMC (and in MO better), but I imagine they'll amp up the jalapenos in anything. Both places have excellent Mexican shrimp cocktails -- i.e. shrimp, red sauce and avocados. Oh, and while it's not spicy, thumbs up for the tres leche cake at El Tio.
Little Mexican Cafe
581 Main St, New Rochelle, NY 10801
25 Anderson St, New Rochelle, NY 10801