If starting with fresh green beans that need to be trimmed, rinse them, snap off the ends, and peel off the strings. If starting with trimmed green beans in a bag, just proceed to the next step.
Boil the green beans for 10 minutes or follow the microwave instructions on the bag to steam them. You also could steam fresh green beans by placing them in a microwave-safe bowl with three tablespoons of water, covering with plastic wrap and cooking on high for 5-6 minutes. Drain any cooking water and pat the green beans dry with a paper towel.
While the green beans are cooking, peel the garlic and finely chop it.
Heat the oil in a 12-inch skillet on medium heat. Add the garlic and let it cook for a minute, stirring and being careful not to let it burn. Then add the green beans, salt and pepper. Stir to combine and raise the heat to medium-high.
Let the green beans cook uncovered in the pan while you prepare the tomatoes. Use a slotted spoon to remove five peeled tomatoes from a can and add them to a small bowl. (Save the rest for another use.) Break up the tomatoes with a spoon. Drain the extra liquid in a fine mesh strainer and discard most of the seeds.
Push aside the green beans in the pan, making room in the center. Add the tomato pieces to the middle of the pan. Let them cook down for five minutes, stirring as needed so they don't stick.
While the tomatoes are cooking, rinse the parsley, discard the stems, and cut it up with scissors (or chop it).
Stir the cooked tomatoes into the green beans. Taste a green bean to see if it's done. The green beans need to be tender but not mushy. They should be able to bend easily. Cook for a few more minutes if needed.
When the green beans are done, turn off the heat. Stir in the parsley.
Serve the green beans at room temperature. If desired, you can serve it with grated Parmesan. It's great with bread to dip in the oil from the pan.
Store leftovers in the refrigerator for up to four days.
Canned tomatoes will provide more of a sauce effect than fresh tomatoes. I prefer the canned tomatoes here for that reason.The citric acid in the canned tomatoes will make the green beans turn yellowish. If you steam the green beans instead of boiling them first, they'll be greener.