Winter vetch aka hairy vetch (Vicia Villosa Roth)... it is a legume and one of many options for cover cropping. It is usually planted with a wheat or rye which acts as a nurse crop. ( A nurse crop is an annual crop that grows more quickly and provides shelter for slower germinating perennials. It basically helps with weed control, prevents soil erosion, shelters tender perennial seedlings, etc.)
So vat's vid da vetch? Well, aside from acting as a green manure and adding nitrogen back into the soil... as a mulch... it makes your tomatoes taste better. (yes, I realize the squints just adore their transgenic plants and glowingly tout the health benefits of purple tomatoes created with snapdragon genes spliced in... but every now and again they stumble upon something that doesn't trigger flashbacks to the movie "The Fly").
Tangent... speaking of transgenic plants... really it is an evil humorous thought I just have to say.. Sometimes with their crazy pairings and compulsive need to meddle with meshing totally incompatible species it makes me wonder how they would handle if the results were actually their kids? "No need for a nightlight with this one Bob, we spliced in a few glowbug genes" or "Hey Gary, you child now will have incredible eyesight, mind blowing reflexes but may not be able to comprehend math. Oh and it is possible later generations may need special footwear and be prone to seasonal molting."
Back to vetch lol.. it can be used as a living mulch too. Having a built in nitrogen dispenser is always a good thing. Just heads up if you try it... vetch has a tendency to not all sprout at once. As in they can sprout in following years especially in areas where it doesn't get cold enough in winter.
So if you are trying to grow tomatoes with amazing flavor and seem to have troubles no matter the variety... the problem is most likely your soil. Give vetch a try. (Gotta love things that do multiple jobs! Honey bees forage the flowers, some vetch plus the grain crop grown with them make good feed for various livestock, compost additive, use as a living or dried mulch, helps break up soil, nitrogen fixer, weed suppressor, reduces soil erosion, and the flowers are cute to boot!!)