Moroccan - Kasbah Grill in Irving - Tagines and couscous dishes are very good
If you don't mind a smokey atmosphere then Mr. Max in Irving is good for Japanese style curry.
Indian - would head over to Samosa Hut....great samosas and decent spicy chicken tikka masala (just don't eat the naan). If you are looking for more of a sit down place then you can go to Amruth, Pasand or Our Place. All of them have lunch buffets but dinner prices go up and you are on your own to explore the dishes.
Mexican - I really like how La Margarita in Irving takes the tex-mex spin on things and makes them a bit more mex. I really like the duck carnitas and the pulled pork relleno. Dishes are always pretty solid. You could also try out the new sister restaurant Mi Dia From Scratch in Grapevine. It is hard to know what to recommend.....I pretty much liek all the dishes I have had there.
If you are down for Mexican style chicken then head for El Pollo Regio or Dona Lencha If you are feeling a bit more adventurous there are plenty of taquerias in Irving that would quench your Mexican cravings.
Nepalese - Everest in Irving is about the only place that still serve fairly decent Nepalese food.
Thai - Bangkok Orchid - I stick only to the authentic thai menu....go for dishes like pad cha, fish nuggets in red curry, or yum pla duk foo (fried fish salad)
Nearby Grapevine has a number of restaurants, unfortunately, many are closed on Sunday, but these aren't.
Steak - Old Hickory (reservations, Gaylord Hotel)
Italian - Ferrari’s Italian Villa, Fireside Pies - nix the pies. superb apps and salads - large/sharable)
Mexican - MiDia, Baja Grill
American - Winewood