My garden's not going gangbusters this year, and I missed the farmer's market on Saturday...but I've still got home-canned goods from last fall, so that's what I used for cooking the sausage.
Aren't these Roma tomatoes pretty? I'd like to have enough to make sauce, but so far there are just a few ripe ones here and there.
Here's how I cooked the sausages: Two pint jars of my home-canned tomatoes went into a pan, and I broke them up a bit and got them simmering. Then I added one green bell pepper and one red pepper cut into strips, and about a third of a jar of a chunky non-spicy home-canned tomato salsa (tomatoes, diced onions, peppers...). Simmered that for a while, then added four pieces of Italian sausage that I brought home from Chicago. Simmered that until the meat was done and the peppers were getting softer. The sauce was a bit chunky since it hadn't cooked for terribly long, but it had a lot of flavor.
Often, when I cook Italian sausage for sandwiches, I use tomato sauce rather than whole tomatoes, but I didn't have any on hand, and I did have the whole tomatoes...so...that's what I used. If you have tomato sauce, use that. Or tomato paste thinned with water. Or whatever works for you.
You might note that I didn't add any seasoning to the sauce besides what was in the salsa. I find that if the Italian sausage is good, it adds plenty of flavor to the tomato sauce. And really, the tomato sauce is a condiment for the sausage sandwich, it's not the star of the dish.
If you want more flavor in the sauce, basil, marjoram, oregano and/or fennel would all be nice. Add salt if the sauce needs it, but the sausage might be salty enough to season the sauce, so taste it before you salt it.
Oh, you want a recipe for the buns? Be patient, it will be up soon.
On the side, I served some sliced cucumbers and tomatoes. Since they were so fresh, there was no need to dress them up at all.
I might break up the left over sausage and serve it with the sauce over pasta for the next meal. We'll see. The leftovers might not make it past lunch.