Heat the oil in a large frying pan, and add the diced vegetables. Cook over a medium heat for at least 5 minutes, stirring regularly, until the veggies are soft. Add the smoked paprika, chilli powder and cumin, and mix to combine.
Spread a generous dollop of refried beans along the centre of a large tortilla, and add about 1/6 of the vegetable mixture. Roll tightly, and place seam-side down in a large baking dish. Repeat with the remaining tortillas, beans and vegetables.
To make the jalapeño cheese sauce, melt the butter in a small pan, over a fairly low heat. Add the flour, and whisk together to form a paste. Cook for a minute or two, then add the milk a dash at a time, stirring until smooth each time before adding more. When you've added all the milk and the sauce is smooth, add the grated cheese and chopped jalapeños. Mix well until the cheese has melted. Season generously with salt and pepper, and adjust the consistency of the sauce with a dash more milk if required.
Pour the jalapeño cheese sauce over the rolled tortillas, and top with halved cherry tomatoes or slices of tomato. Bake at 190°C (Gas Mark 5 / 375°F) for around 30 minutes, or until cooked to your liking. Serve with chopped coriander (cilantro) if desired.