Asklemmy

I don't put tomatoes in salad or sandwiches (I don't pick them out if they are in, but don't affirmatively like them, texture and taste).

Onion and cheese are my non-negotiables in a sandwich. Pickled jalapenos or cucumbers can sub for tomato IMO. Fancy mayo can also be good for adding interest to a sandwich, or compound butter if you prefer.

For a salad, whatever the fuck you want can go in a salad! There is an Italian salad that is just shaved fennel, onion, oranges, and olives. I actually like it but my point is, if that can be a salad anything can. Also - if you like the taste of tomatoes but not the gloppy seed part, you can scoop that out of the tomato slices or just use the outside part and cut out the middle, like you would do with a bell pepper.

How do you feel about sun dried tomatoes?

Cucumbers. You can pickle it, eat it raw, semi-pickle it (google Polish 2 day dill pickles). Or try raddishes if you want stronger flavours.

Side note:

gooey and seedy

That's not a tomato. A proper tomato is firm and sweet and not uniform in shape or colour. Source: am eating some right now, took me forever to find seeds.

The shit we are sold as tomatoes are bulldogs of tomato family. Crossbred damaged line created to maximise profit and decrease production cost, by sacrificing quality and taste.

If you want the umami rich sour sweet flavour, use peppers (paprika) it's not the same, but it's a good alternative.

Grilled slab of portabella adds a lot of juice and umami without being gooey.

If you only don't like the gooey and seedy texture, try dry tomatoes in oil: they get rid of the seeds, of all the liquid part, and become a little harder, but they are stronger in taste.

If it’s a texture thing, have you tried all the tomato varieties? Like Roma tomatoes have very little seed and pulp, cherry tomatoes are kind of like grapes, and I’ve even tried some obscure varieties that make me question what a tomato is.

If that doesn’t work, I’m honestly having a hard time thinking about a substitute for a tomato. They are pretty unique.

To get the sweet yet acidic flavor, I would try a small drizzle of something like red wine vinegar. It wouldn't add much body to the sandwich, but it can really give a great flavor.

If you want more than meat and bread and don't want tomato... Cucumber would add some body with a weak neutral flavor.

red bell pepper

You don't like the texture or the taste? use cherry tomato, they're much sweeter, more flavorful and have more flesh/water ratio so so theyre less wattery (or a plum tomato) An alternative is to incorporate as a spread make a fresh salsa, or a red pesto you'll get tomato flavor without weird texture.

If texture is your problem, try sun-dried tomatoes. Get good ones that aren't dried into fruit leather and you can slice thinly and use as you would raw. Otherwise, they can reconstituted in warm water in a few minutes. Remember they're dried and have very concentrated flavor so don't use the same amount by volume as you would raw.

Cucumbers or radishes?

Sounds like the issue is texture rather than taste, so the obvious answer is cherry tomatoes because they don't have anywhere near as much pith. However, thinking about the role the tomato plays, it's kind of a juicy sweetener with some vegetative notes, so now I'm thinking maybe slices of certain green apple varieties, maybe with something very vegetal, like a leafy green, or maybe a kolrabi, or less so with some spinach or sprouts? Experiment if you have the time and money. Lots of flavors to play with.

For salad, consider cherry tomatoes. For a sandwich, consider a tomato relish. Big, but similar flavour profile, but different texture.

Husband also hates mealy and watery tomatoes and my only solution so far was home grown paste tomatoes, like san marzano type tomatoes. Much less watery overall.

Tomatoes are mildly acidic, so something similar should get you an approximation of the flavor. Pickled onions might be a good choice, or some other lightly pickled fruit/veg (maybe beets for salad). Actual dill pickles are not going to be too acidic to be a good substitute (but are a great thing to put on sandwiches in addition to tomato anyway).

Pineapple might work in some cases, but it has a strong flavor and sweetness that won't work everywhere a tomato does. Salsas are a good place for this as a tomato substitute (along with mango and corn), but pineapple does also work well in some sandwiches.

Persimmon.

Well, for sandwiches you can put them tomatoes-up under a broiler for a few minutes. You'll still have tomatoes, but they won't be raw. It improves the texture and deepens the flavor significantly.

Bacon

I can't tell if you actually have an allergy or just don't like them. There are a lot of different tomatoes so I'd explore those including Tomatillos if you aren't allergic. If you are allergic. I'd start looking at persimmons, zucchini, eggplant, maybe peppinos even some more mild apples. Don't go for "sweet or tart".

Tomatoes provide acidity/sweetness, depth, and moisture, so anything thing or combination of things that provide that can substitute. Pickles provide acidity and moisture, but not the rest. Mayo & mustard mixed kinda gets you in the ballpark. Red bell pepper provides brightness and sweetness... Start trying things along those lines to begin with.

I love tomato myself, but if I couldn't have it for some reason or my tongue betrayed me one day, I'm thinking lightly pickled eggplant might get close to the same niche.

Raw tomato is has the slight crunchy sensation and fresh mouthfeel of many raw fruits/veggies, and the flavours are mostly acidic, sweet and unami. I don't know what else might set off your sensitivity issues, but I think some options might be pickles, or fresh cucumber slices dressed with nice vinegar. Or use a combination, like iceberg lettuce for crunch and some relish or chutney for flavour.

To-mah-to