Trim both ends of green beans by cutting them ¼- ½ inches. Rinse under running water, drain, and set aside.
Finely chop 2 of the onions. Peel the other one and leave it as a whole.
Heat the oil in a large Dutch oven (or any heavy bottom pan) in medium heat.
Add in the onion, and stirring occasionally, cook until translucent, 5-6 minutes.
Stir in the paste, diced tomatoes, salt, black pepper, sugar, and water.
Add in the green beans. Give it a gentle stir making sure everything is homogenously distributed in the pan.
Place the reserved one onion on the top and put the lid on. Let it come to a boil and turn down to heat to medium-low and cook until the beans are tender, 35-45 minutes. Make sure to give it a gentle stir a couple of times during the cooking process.
To make the yogurt sauce: Whisk everything in a bowl, taste for seasoning, and add if necessary.
To serve: Place the green beans on a plate and top it off with yogurt sauce and some fresh dill.