My wife and I (age 74) will visit Madrid for the first time May 1-7, 2019. We will eat our "big meal of the day" in early afternoon since we will go to bed before others eat their culturally-late evening dinner. Otherwise, we will "graze" as needed while we move all day between attractions/neighborhoods. Ideally, looking for smaller restaurants serving reasonably-priced meals with vegetables & fruit. We love Tapas but don't want to have them daily. Thanks in advance to all who respond!
Is this your first time in Spain?
If you want a sit-down set menu for lunch then you might consider the restaurants in any of the larger hotels that you will walk by when you're walking east-west from your hotel to the Prado, like the Westin or the Radisson.
If you want to try out more local experiences then go south from your hotel to the area around the Museo de San Isidro or the plaza de las pajaros and pick a spot on the square.
--Note that tomorrow is the feast day of St. Isidore of Sevilla so the Museo de San Isidro is well worth checking out!
You may want to eat earlier as the siesta is popular in Madrid and many restaurants will be closed from about 2 or 3 until at least 7 or so. We are older than you but find we love the idea of the siesta and the eating patterns in Spain.
You might consider El Cortes Inglés. The top floor has a bar and "food court-like restaurants." Lovely view as well. Variety of food options. I had a nice Vegetable Paella. Walking distance from Puerto del Sol. Incidently, we went to the El Cortes Inglés in Barcelona. The basement of the stores have a wonderful market.
I'm going to have to take up some of these recommendations for my trip later this year.