If prepping bell pepper and tomatoes same day: pre-heat oven to 400 degrees. Slice tomatoes into halves and arrange on a rimmed baking sheet lined with parchment.
Cut and de-seed bell pepper and slice bell pepper lengthwise. Arrange on baking sheet with tomatoes. Season with olive oil, salt and pepper and, using your hands, toss together to mix.
Roast tomatoes and peppers in oven for 20-25 minutes, until tomatoes are blistered and peppers have slightly charred edges. Remove from oven and allow to cool slightly.
While the tomatoes and peppers cool, place garlic, nuts, and red pepper flakes in a food processor fitted with a steel blade and pulse until the beginnings of a paste is formed.
Add in the slightly cooled tomatoes and peppers along with the smoked paprika, vinegar, salt, and pepper and process until smooth. With the processor running, slowly add in the olive oil in a slow stream through the feed tube, until sauce is well amalgamated. Taste and adjust seasonings.
Once the sauce is at a flavor profile you like, scrape into a bowl. Let stand for an hour at room temperature to allow the flavors to marry.
Though the sauce takes a good chunk of the prep time, everything else comes together quite quickly. For the cod, arrange fillets on a baking sheet lined with parchment. Season with salt and pepper and drizzle olive oil. Roast in a 350 degree oven for 15-20 minutes.
Spoon a bit of sauce on your plate. Layer with the cauliflower steak, the fish, and a bit more sauce. Enjoy!
