For the filling; Mix diced onions, rice, ground meat, 1 tbsp tomato paste, lemon juice, chopped dill, mint, and half of the chopped parsley, olive oil, salt and pepper in a bowl.
Wash the zucchinis and cut them into two, then scoop out their pulp with a small spoon and set aside. The walls of zucchinis shouldn’t be too thick or too thin (about 1/4 inch). Wash the peppers, cut out the stems, and remove seeds. Sprinkle a pinch of salt inside all of the veggies.
Stuff the vegetables with the meat mixture, being careful not to overfill since the rice and ground meat will expand as they cook. Place each stuffed vegetable upright in a large pot. Sprinkle the reserved zucchini pulp around pot. Add can of tomatoes.
Pour broth or water into pot until the vegetables are 50%-75% submerged. Bring to a boil and then reduce to low heat and simmer for about 40 minutes.
Garnish with remaining chopped parsley and serve with yogurt.