I think you were disappointed because the most famous Lao dishes have become popular in Thailand and a lot of the food you find in Laos without a local to help isn't really Lao food but Thai, Vietnamese, Chinese, and French food.
The most famous Lao dishes have to be larb and green papaya salad. I never saw these on offer in non-touristy Surat Thani in Thailand, but they were everywhere in Khao San in Bangkok and of course in Isan, which has a Lao ethnic majority.
It turns out that all the stir fries you see in Laos are not Laotian. They're all originally Chinese though some have come through Thailand's cultural filter such as pad thai. The same for curries. The ones you see in Laos are due to Thai influence. The same word "gaeng", which means "curry" in Thailand usually means "soup" in Laos.
I don't think French food has influenced Lao food greatly, it's mainly stayed separate. But when I finally found where to buy local baguettes around the bus station, I barely recognized any of the ingredients.
Apparently the main staple Laos regard as Lao food is the sticky rice (khao niao). I thought I'd had sticky rice before because some rice is stickier than other rice. But the sticky rice here comes in little woven pot/baskets, is super duper sticky almost like play doh. Here the staff in my guest house have it every day with a spicy salad, some raw leaf vegetable I can't identify, and some meat or fish. I'm sure this is also in Thailand but again it's a Lao ethnic food that you can get in Thailand - not a Thai food.
But I'm just a traveller sussing out the food here. I'm no expert. Did you wander through the night market in Vientiane and see all this:
One thing I found is a local dish similar to laksa of Malaysia/Singapore/Indonesia. I don't know if it's related or just a coincidence. It's called khao poon:
As an unexpected bonus a Lao who grew up here but lives in Thailand and has pretty good English has checked in to my hostel so we're gonna wander around and I'm gonna ask him about Lao food (-: