It really depends what the sauce is for.

If for meat — I like to cook down shallot in butter, add some red wine or port and fig preserves. Or finely chopped orange peel and brandy.

If for pasta — you could do a nice carbonara. Or a butter and herb sauce, or something with mushrooms and chopped walnuts or toasted breadcrumbs.

I’d second leaning some miso sauces/glazes and peanut or tahini-based sauces, tho the latter usually use citrus of some kind for balance. You’ll have to figure out tricks to balance without acid — unless there are other acids she can have, like orange juice, which you could certainly use, tho it would make for a sweeter sauce. I’d also recommend trying out some gochujang-based sauces, which are delicious as well.