Soup can easily be made in large batches, stored in the refrigerator, and brought to work each day. I have done this numerous times. I will portion some out and reheat it in the microwave, add it to my thermos and bring it to work for lunch. Some filling soup ideas:
In a large pot, simmer some carrots, minced garlic or ginger, onion, and water. Add canned (or dried cooked) white beans to the pot. Continue to simmer for about fifteen minutes until the carrots are soft. Add the mix to a blender (may have to do in batches) and blend until thick and creamy. The amount of water you add depends on the volume of the carrots and beans. In place of the beans, you could add chopped apple, and in place of the carrots you could add any winter squash or canned pumpkin.
You can do the same with green split peas. Saute some onions, garlic, and chopped carrots in a large pot with oil or a little water. Add two cups of dried split peas, and then add about five cups of water. Bring to boil and then lower heat to simmer for about thirty to forty minutes until the beans are soft. Again, add in batches to a blender and blend until creamy. You can make split pea soup as thick or thin as you want it. I like to add ginger powder and lemon juice for extra kick.
There are so many ways to make soup and so many combinations and it is hard to mess up soup. Sometimes I just find what I have and throw it in. Maybe some black beans, tomatoes, mushroom, zuchini with Italian spices and water. Or maybe beets and almond milk. Or chili with pintos, black beans, bell peppers, onion, mushroom, fresh tomatoes, canned stewed tomatoes, tomato paste, quinoa or bulgur wheat, taco seasoning or chili powder, cumin, etc
Homemade breads or cornbread etc goes well with soup, or homemade crackers, or buy all those items to go with it. Vegan bread can be a challenge to find commercially but there are some out there. Often in the bakery of groceries, ciabetta bread or some French breads are naturally or accidentally vegan.
This week I made a huge garden salad and added several cups of chickpeas, some sesame seeds, and made my own orange dressing. I portioned the salad into five containers and bring them to work each day, along with side snacks and so on for lunches. It took maybe twenty minutes to make the salad and add it to five containers. You could bring a plant milk to sip on too, or a smoothie and so on.
I was misdiagnosed with IBS for five years before having a laparoscopy due to extreme pain and it turned out I had severe endometriosis on my bladder, various ligaments, uterus, housing around ovaries, and even on my colon. The ebb and flow of hormones throughout my monthly cycle was aggravating the endometriosis lesions and causing pain and digestive issues (which is common for endometriosis). But my diet was also terrible at the time. I was so afraid of aggravating the cramping, bloating, nauseating pain I had all the time that I would eat the most bland food there is. I rarely ate raw vegetables and was living on white bread, potatoes, bananas, yogurt, lactose free milk and then almond milk when that came along. And all it did was cause constipation which in turn increased the pressure and pain down there. Those days are long gone thankfully but i can understand the digestive problems! I wish I had dramatically changed my diet back then instead of after having all my reproductive organs removed and suffering now with osteoporosis many years later. I remember I used to eat the same foods all the time back then too. I was so afraid of upsetting my stomach.
My favorite breakfast that I always talk about here is simply mixing a banana and cooked sweet potato or pumpkin (canned is fine) together. Maybe add some cocoa powder in there, or molasses, or anything else that sounds good. You could also add it to oatmeal. I find it to be very filling and satisfying. And it might be easy on your tummy. You could have smoothies too and add soft leafy greens to them to get in roughage in a liquid form without upsetting your stomach. Frozen bananas, cantaloupe, peaches, apricots etc make them creamy and rich. I did invest in a high speed blender and use it to make nut butters, blend flour from whole seeds, make smoothies with whole fruits and vegetables, grind coffee beans, you name it. But a regular blender will make decent smoothies too. You might have to pre soften or slightly steam leafy greens to blend them thoroughly in a regular blender, but I think spinach blends nicely in them if I remember.
Best wishes and I hope a vegan journey heals you!