I recently ate a frisee salad with grapefruit, avocado, and smoked trout at Plow in SF. Does anyone have a similar recipe to that salad?

That recipe is a riff on a Lyonnaise Salad. Doesn't sound like it needs a recipe to me, just gather the ingredients and make a basic mustardy vinaigrette. Sounds really delicious! Thanks for the suggestion. :)

The other way we could approach this is for you to describe more fully what the dressing tasted like and provide suggestions.

The online menu describes it as "Smoked Trout Salad: chicories, grapefruit, avocado, poached egg" and provides no description of the dressing.

If you do a Google image search for "trout salad plow" at least three of the first four images show the dish at the restaurant.

https://www.google.com/search?q=trout+salad+plow&biw=1272&bih=657&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiYgrC4x5bNAhVJz2MKHbh3AXEQsAQIMA#imgrc=xnb1Sh5ppDqIbM%3A

Based on these it should be easy to prepare most of the necessary ingredients: smoked trout crumbled into bite-size pieces, frisee (chicory), chunks of avocado, grapefruit segments, and a poached egg or two.

Not knowing what sort of dressing was used, I'd be inclined to use a lighter vinaigrette, perhaps something based on white wine vinegar or lemon juice.

The photos themselves do not indicate that Plow used a creamier sauce or anything with a darker acid (like balsamic).

It does seem like there are some seasonal variants. There are pomegranate seeds in one shot, watermelon radish slices in another, so likely the restaurant keeps this salad on the menu as a staple and changes a few of the items to match seasonality.

Try this one and substitute frisee for the arugula: http://www.foodandwine.com/recipes/smoked-trout-salad-with-avocado-and-grapefruit