Miso-tahini with lemon is my go-to sauce to accompany my steamed vegetables. I like to make enough to last a few days, as it keeps that long and I love always having it available. It adds a nice nutritional and protein boost to the veggies, along with other protein I might eat for the meal.
I discovered a really wonderful tahini last year called "Soom" (available on Amazon). It is just supreme - so smooth and delicious, and of course more expensive than other brands. What I do for this sauce is mix the Soom half-and-half with another kind of tahini. Right now I am favoring a brand called "Once Again." The combo works well for this sauce.
When it comes to the miso, I have always found the Cold Mountain brand to be excellent. I use their Mellow White miso (I tried yellow once, no, not good for this sauce!). The miso keeps for a very, very long time.
This is a very simple sauce to make - it can be easily done while veggies are steaming so everything's ready at once. I like adding fresh herbs from the garden - usually parsley, sometimes garlic chives (or both) - whatever your heart desires.
Make sure your tahini is stirred to a well-mixed constitution in the jar before using. Place 2 Tb of the tahini in a bowl with the water and stir well with a fork until very smooth.
Add the miso paste and lemon juice to the tahini mix and stir well to combine. Taste for each ingredient and add as needed; if too thick add more water or lemon juice.
Chop the parsley into small bits and add to the miso-tahini mix along with the toasted sesame seeds. Or add any herb/seed/nut mixture you like to the sauce, to your liking.