Years ago when I was still living in Seattle, my partner and I would go on walks to different neighborhoods for things like buying new plants, trying out new restaurants, going to farmer's markers, looking at consignment shops, etc.
Once we learned of Royal Grinders in Fremont, we got into a regular habit of going there whenever we had any excuse to. To this day, if I'm visiting Seattle, I'll try to find a way to plan getting a sandwich there before just about any other restaurant.
Royal Grinders is a sort of hole-in-the-wall sandwich shop that's tucked into the corner of an outdoor picnic area next to the Lenin statue in downtown Freemont, a neighborhood North of downtown Seattle and across Lake Union. Inside the small space there are a couple stools to sit on, a bathroom, and then the rest of it is just prep area for these sandwiches. Importantly, there is a yelp review posted at the counter for people to read while they wait explaining that their sandwiches take a long time (about 8-10mins) to make.
There are plenty of options on the menu, including hot sandwiches with meat or veggies, and a gluten free bread option as well, but the only sandwich I've ever been interested in eating from there ever since I first tried it is the Chicken Pesto Grinder.
This sandwich has chopped chicken as the protein, some melted provalone and swiss cheese on top of that, then sliced tomato and pepperoncini and red onions, served with a spread of pesto and some drizzled "zesty grinder sauce" (a "garlic ranch Italian dressing") on an herb-roasted French bun. In addition to all of this, there are sliced black olives in this sandwich - something I do not enjoy on pretty much any other food, yet here it adds just enough sweet to balance out the savory herbs and chicken and the spice of the pepperoncini and red onion.
Since moving away, my partner and I have tried to remake this sandwich at home and it's pretty good, but we have no way to make the bread. It has just enough of a crust to toast nicely, but it keeps the internal nice and chewy.
If you're in Seattle and you want something only about a half-hour walk downhill from my previous recommendation of Kouign Amanns, you should go check it out