Translation:Tini is cooking water spinach, tempeh, and tomatoes.
Tempeh is the food of the gods, made by having an edible mould (rhizopus oligosporus and/or rhizopus oryzae) grow over soybeans to ferment and bind them together into a kind of block. It's delicious! https://en.wikipedia.org/wiki/Tempeh
"Water spinach" is a kind of Asian green: https://en.wikipedia.org/wiki/Ipomoea_aquatica
And it makes more sense to translate this to English "tomatoes" because dish names in English always use the plural or a collective noun. Even if you used a single tomato in the dish, if you named the dish after it, you'd still say "tomatoes" in the name.
i agree that tomatoes should be plural. But what is water spinach. In English it is sufficient to say 'spinach'.
Because its not actually spinach, I had never heard of it before but a quick google search reveals that it is more closely related to the sweet potato than actual spinach. My own preference in such matters is to use the native name rather than an ambiguous and confusing Anglisiation, e.g. tempeh is not translated here as fermented soybeans. These days Google will in very short order tell you what you need to know.