Preheat the oven to 250 degrees F. Line a baking sheet with parchment paper. Arrange the tomato slices on the baking sheet. Set the garlic, bread and almonds on and around the tomatoes. Drizzle all with the olive oil, and then bake for 90 minutes.
Place the roasted tomato mixture, ensuring you get all the juices from the pan, in a food processor. Add the peppers, vinegar and chili flakes. Pulse the mixture until smooth, adding a little more oil if too thick. Season the romesco sauce with salt and then transfer to a serving dish.
Season the steaks with salt and pepper. Lightly oil your grill. Grill the steaks to the desired doneness, and then plate and serve with the romesco sauce. Any leftover sauce can be refrigerated and used over the next few days. It makes a great dip or spread for a sandwich.
Note: Roasted red peppers are sold in jars in the aisle where pickles are sold.