Add vegetable stock to a saucepan and break up the saffron threads by crumbling it with your fingers into the stock. Bring the stock to a simmer and then let it simmer for one minute. Turn down the heat and just keep it warm.
Add 2 Tbsp olive oil to a paella pan. Add in the chopped onions and yellow bell pepper. Sauté until softened.
Add the sliced portobello mushrooms and marinated artichokes and sauté until softened.
Add the sliced cherry tomatoes, sun dried tomatoes, capers, crushed garlic, smoked paprika, sweet paprika, dried thyme and cayenne pepper and sauté for a couple of minutes.
Add the Spanish paella rice along with the remaining 1 Tbsp olive oil and stir so that the rice is mixed in. Cook for a minute to lightly toast the rice, stirring occasionally so that the rice is spread evenly across the pan.
Pour over the vegetable stock with saffron threads and add in the salt and pepper. From this point onwards do NOT stir the rice.
Bring it to a simmer and let it simmer for a couple of minutes before reducing the heat. Leave it to simmer for around 20 minutes until the rice is cooked. You will be able to see the stock reducing in the pan as it cooks.
When the stock has cooked off, use a spoon to gently lift the rice and see if there is any liquid at the bottom of the pan. The liquid should have all cooked off and the rice should be soft but firm.
Remove the pan from the heat. Add the frozen (thawed) peas and black kalamata olives to the top of the rice. Don't mix them in. Cover the pan with foil and let the paella rest for 10 minutes.
Now remove the foil and mix in your peas and olives. Your paella is ready to serve. Top with chopped fresh parsley, lemon slices and ground black pepper.