I would advice, apart from tying out new recipes, try to look at how you cook rice, make a green salad and tomato based sauce again. Often there are a few basic things one can improve that elevate all other dishes as well. This doesn't have to be expensive, you save a lot of money by not buying the meat, after all.

(A few of these things you will probably know, but perhaps you learn something new.)

For rice try the following:

most children prefer basmati rice and rice with tumeric
cumin also tastes good in rice but not all kids like it
most types of rice have to be rinsed a few times, a good job for kids lol
when you let the rice soak in water (~30 min) after rinsing it, you get more predictable results
when you want to fry the rice, use rice you cooked the day before
try different rice varieties from different brands because they all tend to need a different amount of water for best results
when your family really becomes rice fans invest in a good rice cooker because it saves time and older kids can make their own
after cooking, let it steam for a few minutes on the turned-off stove

For a good tomato sauce try the following:

diced or crushed tomatoes in cans often have low quality, when using cans use whole peeled tomatoes and cut them when still in the can
do not crush garlic, instead chop it very fine
use a really good oil, it has to taste so good, you would eat it with bread with nothing else
oil is a whole beast, try different types and be careful which of those can be heated to which temperature
some finely chopped celery often tastes good in tomato sauce
heat very slowly and don't make it boil, don't cook too long
add sugar to taste, baking soda if it is too acidic
add herbs only when the sauce is finished, perhaps add oil again
some people think tomato sauce tastes better the next day

Some tips to make your salad better:

the oil hint from above
for vinegar all the hints for oils apply
mix something crunchy into your salad, many kids love sunflower seeds or peanuts, which are less expensive than walnuts and similar
when you want roasted sunflower seeds, buy them raw and roast them shortly without oil in the pan until you can smell them
wheat grains roasted taste great, they smell amazing as well
top your salad with something hot, for example caramelized pear slices or seasoned tofu cubes, marinated fried champignons, etc.
get a salad spinner if you don't have one already
some children like vegetables raw they do not eat cooked, for example fine broccoli florets and zucchini slices
good mustard or lemon juice on the side

General tips for vegan and vegetarian recipes:

a good rule when it has to go fast is: combine grain + green + bean
experiment a lot with combinations of textures
grating vegetables adds lots of moisture, can be good or bad...
roast whole spices without oil until their smells hit you before you cut them and put them into your dishes
make your own vegetable broth by freezing clean vegetable scraps (skins and ends) and simmer them when you have a bag full
maple syrup + non-dairy milk mixed make a crust on baked goods
infuse oil yourself with herbs, chilli, garlic
learn to sauté a base of spices, garlic and onions before adding your ingredient
learn how to make natto, get used to the taste and then addicted to it
now that you are a pro with herbs, make your own fresh tea and experience a new world of taste

Ingredients which you perhaps never used before but are very useful:

nutritional yeast !!
soak and blend cashews for a versatile cream base
Kala Namak
liquid smoke
miso
tamari
seaweed
the water from chickpea cans is aquafaba