Ah we are opposites! I find white potatoes the blandest food on the planet, I much prefer the colourful sweet potatoes.
I almost always roast them dry and toss them into whatever I am making - be that pasta or on the side with other vegetables. I love dhal, especially because it's easy to batch cook and refrigerate or freeze. This is one of my go-to recipes, although I often substitute the potato for butternut squash.
A comforting vegan one-pot recipe that counts for 3 of your 5-a-day! You can't go wrong with this iron-rich, low-fat, low-calorie supper
www.bbcgoodfood.com
Seitan is another good thing to batch cook once you have a method you like. I tend to make it plain, portion it out and freeze it - then throw it into whatever I'm making. You can slice it thinly and have it in sandwiches. I don't have it that often, as I'm not sure that much gluten is ok too frequently.
Most of our meals tend to be casserole-style dishes; a big pan of beans and vegetables. Easy to prepare and good for lunches with leftovers.
Dr Greger is my go to guy when I'm looking for advice online, and he always recommends whole foods. His book 'how not to die' is excellent, and you can get it on audible with a free trial.
I do take b12, and I think it's probably a good thing for most people to supplement.