In a small saucepan, heat oil over medium-high heat. Sauté mushrooms until liquid is evaporated, about 3 minutes. Add zucchini, garlic, half of the salt and the hot pepper flakes; sauté for 1 minute. Add passata; bring to a simmer. Cook, stirring occasionally, until zucchini is tender, about 4 minutes. Remove from heat and set aside.