Flavors and textures. Veggie food tends to be bland. Show variety to dispel that expectation.
For starters fry some grain and legume dumplings. Falafels are great. Get a can of chickpeas and a bottle of sesame oil. Mash the chickpeas and make a dough with lemon juice, salt, and a little flour if it doesn't stick. Deep fry tea spoon sized balls. Serve with condiments like hummus or mint yogurt.
Then a soup is great. Any cream soup is good, pumpkin, leek, roots. spinach, ... Always boil for at least 40 minutes with white wine, laurel, juniper, carrot, parsley root, leek, celery root, and garlic. Then fish out leek and celery, laurel, and anything that doesn't blend. Stick the immersion blender in, add some cream, and finish with salt, sugar, and lemon juice. Fry some croûtons (extra plate) and garnish with cut herbs.
After that a small lasagna maybe? Find a video for béchamel sauce, the rest is just layering pasta, tomato sauce, any veggies really (mushrooms, aubergine, zucchini, spinach, ...) and cheese. Throw in oven for at least an hour on low and raise heat to finish cheese crust.
For desert maybe a fresh fig with yogurt, honey, and cinnamon?
If that doesn't do it finish with a cheese platter. Vegetarians love cheese more often than not. Get some variety, it doesn't have to be expensive. Camembert and some hard cheese is available anywhere. See if you can also get some goat cheese and maybe a cottage cheese mixed with some herbs.
It's all in the presentation. Serve small portions on large plates, decorate with herbs, salad, pepper, be bold but stingy with the sauce, and have wine ready. Read up on your wine. Get something with the name of the grape on the label, no blend.
The soup and lasagna you can prep completely and only need to heat before serving, neither will suffer from reheating. Falafel should be made fresh, so just prep the dough and maybe test it out for lunch before. It's a nice kitchen presentation and will be done to sit down.