Why do you need a recipe? It sounds like you KNOW what you want. Just put the things in that sound good to you - it should be just fine.
If you like a mayo-based dressing, just use mayo and maybe the tiniest splash of vinegar (unless you don't like the tang).
I would season with a little onion, salt, pepper and dill, to taste, but the beauty of pasta salads is pretty much anything goes.
Good cooks taste as they go. That's the only way to discover what you like, what seasonings work together for you, and how much of certain things you need...
One more thing:
I guess I don't know if you're going vegan or vegetarian... If you're looking for a VEGAN alternative to mayo, there are several options:
My absolute favorite Vegan Mayo is Vegenaise, which gets VERY good reviews by most vegans here on VB
- try the grapeseed oil version if you can find it - SOOOO tasty!!.
The other popular one is Nayonaisse, which some people like better - I don't care for it as much, you'd have to decide for yourself. There is also one made by Spectrum and one from Trader Joes, but I don't know much about them.
I really find it hard to believe there isn't a recipe out there that's close to what you like, but if not, just make it up! Seriously, just experiment. It'll be fine!