Cook Base - Add olive oil to the paella pan or skillet. Heat over medium heat. When oil gets hot, add in onion, garlic, and red pepper. Cook 3 minutes. Stir in mushrooms and zucchini and sauté another 3 minutes. Stir in paprika and quickly add tomato, peas, rosemary, and season with salt and pepper. Sauté another 3-4 minutes to thicken the tomato up a bit,
Cook Rice - Add rice to vegetables, stir to coat and cook for 2 minutes. Increase heat to high and add broth and saffron. Stir to combine once but don't mix again. Boil until most of the broth has been absorbed by the rice, 9-10 minutes. Lower heat to medium-low and cook, undisturbed, about another 5 minutes until all the broth has been absorbed.
Finish Paella - Turn heat to medium-high and cook an additional 2 minutes to (hopefully) achieve a socarrat- the fought over bottom layer of crunchy caramelized rice. Remove from heat and leave untouched for 10 minutes, covered by a dishcloth or tin foil. Garnish with parsley and lemon wedges. Serve in the paella pan with a big spoon.