I'd avoid the mushroom risotto, mushroom is a commonly hated ingredient and mushroom risotto is EVERYWHERE at the moment as a vegetarian option
As a vegetarian please don’t feed us a mushoom risotto or a veggie lasagne, they are generally the only option when we go out
See?
Veggie lasagne I've had soooooo many times as the only option (in over 30 years as a veggie) that I honestly can't face it without balking to be honest!
Thing is, when I look at the recipes they don’t look particularly filling
You sound like my gran there to be honest! She thought you NEEDED meat to feel satiated!
A vegetable stir fry can be hearty and satisfying IF you make a proper effort with it and put in a wide and plentiful variety of veg. Thickly chopped Pak Choi, peppers, bamboo shoots, water chestnuts, spring onions, mushrooms (if they like onions), a good home made sauce (tons of recipes online, super easy to do for a good cook), a well cooked side of carbs (noodles, rice) and perhaps some appropriate sides and you're good to go
Pasta but please don't do a boring tomato sauce you'd be doing your guest and yourself a disservice. Do a really good rich tomato sauce - I'd advise make it ahead of time as the longer the flavours have to develop the better it tastes. Again loads of recipes online. Make it a bit special with some really good antipasti on the side like artichokes, stuffed olives etc
Vegetable soup is good for lunch/starter. I'm a scot we love our soups. I hate getting an insipid poorly seasoned one though (which as a veggie often happens!). I make a spiced butternut squash and carrot blended creamy style soup that my dd loves. Or a scotch broth but without the meat. Minestrone usually goes down well or a spiced Thai style soup
Mexican - is perfect if serving veggies and omni's as people can pretty much serve themselves. You can make a veggie chilli (as she's not keen on beans use a soy or Quorn mince - very easy to work with, it doesn't have to have kidney beans in it indeed purists say a chilli should never have beans!) and an omni chilli, have tortillas and taco shells available to choose, some sour cream and guacamole, grated cheese, shredded lettuce, corn on the cob (delicious with a little smoked paprika sprinkled on and grilled), rice, a gorgeous home made coleslaw, refried beans for those that do like beans, smoky baked beans (juj up normal baked beans with a little smoked paprika or smoked chipotle, garlic granules, a wee bit ginger if liked)
Curry can work similar to Mexican too, have a veggie curry and a meat curry and lay out/make popadoms, naan bread, rice, raita, spiced onion salad, samosas, pakora...
LOTS of food is vegetarian or can be made vegetarian.
It's so much easier these days to when I first went veggie.
Don't assume desserts are veggie. Lard, cochineal, gelatin etc so check labels (or of course make from scratch. Few will turn away a lovingly made cake/scones/pastries)
A vegetable tart if well made will go down well and is very easy to make. You could even do a Sunday roast with a tart or nut cutlet or Quorn item instead of meat, make sure the roast veg stays veggie (no goose fat) lovely Yorkshire's, sage and onion stuffing is veggie or you could make your own I love sage and onion stuffing balls myself.
Veggie toad in the hole is yummy too, Linda McCartney sausages are my favourite
Or a casserole - cook meat separately for the omnis. Very easy to do especially if you have a slow cooker. Again loads of recipes online, I never really make the same one twice! Just whatever root veg I have in plus other veg that would be suitable, Quorn pieces if I fancy, stock, seasoning, whatever herbs and spices I fancy/have in and cook for about an hour (conventional oven) serve with roast potatoes (again keep them veggie) or even home made crusty rolls with good butter