Heat the olive oil in a traditional paella pan or a wide, shallow skillet over medium-high heat.
Add the cubed seitan and sear for 4-5 minutes, stirring occasionally until the pieces are golden and slightly crispy.
Lower the heat to medium and stir in the diced onion and red bell pepper, cooking for 5 minutes until the vegetables are tender.
Stir in the minced garlic, smoked paprika, sea salt, and black pepper, toasting the spices for 1 minute until fragrant.
Add the tomato puree and cook for 2-3 minutes, allowing the flavors to meld and the sauce to thicken slightly.
Scatter the Bomba rice across the pan in an even layer, stirring briefly to ensure every grain is coated in the tomato base.
Mix the saffron threads into the vegetable broth and pour it over the rice; do not stir the rice again from this point forward.
Simmer the paella for 15-18 minutes over medium-low heat until the liquid is fully absorbed and the rice is tender.
Allow the pan to sit for an extra 2 minutes to develop the socarrat crust, then garnish with fresh parsley and a lemon wedge.