Trim squashes and cut into small 1/4-inch dice. Heat 2 tablespoons olive oil in a frying pan and add 1/3 of the diced squashes and some salt and pepper. Saute small batches briefly over high heat stirring often until lightly browned and slightly soft. Transfer to a bowl. Cook diced onion in remaining olive oil in frying pan over medium heat 3 to 5 minutes. Stir in garlic and cook briefly. Add cumin, reduce heat to low, cook stirring about 2 minutes, and then add to squashes in bowl. Add rice and chopped parsley and adjust seasonings. Serve immediately.