Santiago Lastra shares his recipes for cheesy mushroom costras and beetroot tostadas

Santiago Lastra: what to know

Cheesy Mushroom Costras

Costra, meaning ‘crust’ in Spanish, is a traditional dish from northern and central Mexico. It is typically made with tender cuts of beef and topped with a melted crust of semi-hard cheese, often a mix of Chihuahua or manchego with Oaxaca cheese for texture. In this recipe, mushrooms replace the steak.

The mushrooms are roasted and then flattened before being topped with melted cheese. The cheese is cooked on a plancha grill until it melts and crisps up, creating a flavorful crust.

Ingredients for Cheesy Mushroom Costras

• 6 portobello mushrooms
• Vegetable oil, for drizzling
• Flaky sea salt
• 12 x 15cm flour tortillas
• 200g emmental, grated
• 50g coriander or chervil, stalks included, finely chopped
• ¼ onion, finely chopped
• 100g raw salsa verde (see below for recipe)
• 3 lemons, cut into wedges

Preparation Steps

1. Preheat the oven to 220C (200C fan)/425F/gas 7.
2. Place the mushrooms in a baking tray, drizzle with oil, and season with salt. Roast for 20 minutes.
3. Once roasted, flatten the mushrooms with a rolling pin.
4. In a dry frying pan, cook the tortillas for 30 seconds on each side until slightly bubbling. Wrap them in a cloth to keep warm.
5. Divide the cheese into 25g balls. Spread one ball in the pan to create a circle the size of a mushroom. Cook until slightly melted, then place a mushroom on top.

Beetroot Tostadas

Tostadas are traditionally made with crisp corn tortillas, which can be baked or deep-fried. In this recipe, poppadoms are used as a substitute to achieve a similar texture and starchiness.

Ingredients for Beetroot Tostadas

• 3 mixed color beetroots, unpeeled
• Vegetable oil, for drizzling and deep-frying
• 1 tsp flaky sea salt
• 10 uncooked poppadoms (or ready-cooked ones)
• 1 ball burrata
• 1 bunch soft herbs (e.g., oregano, parsley, chervil, mint, basil)
• ½ quantity pink mole (see below for recipe)
• ½ quantity sesame macha (see below for recipe)

Preparation Steps

1. Preheat the oven to 210C (190C fan)/400F/gas 6½.
2. Toast garlic in a dry pan for 8-10 minutes until charred. Toast sesame seeds in the oven for 5 minutes until golden.
3. Prepare the sesame macha by blending toasted sesame seeds, garlic, and other ingredients until smooth.
4. For the pink mole, roast the beetroots and garlic, then blend with other ingredients until smooth.
5. Deep-fry the poppadoms until crisp and puffed up, about 3 minutes.
6. Serve the burrata dressed with herbs, alongside the pink mole and sesame macha for dipping.

Raw Salsa Verde

This fresh salsa complements the dishes well.

Ingredients

• ½ onion, quartered
• 1 garlic clove, peeled and roughly chopped
• 5 serrano chillies, halved
• 8 small green tomatillos, halved
• 40g coriander, stalks included, roughly chopped
• 1 tsp flaky sea salt

Preparation Steps

1. Blend all ingredients in a food processor, adding water as needed until smooth.
2. Store in the fridge and stir before serving.

Further reading

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