Deep Frying Tofu

Black Pepper Tofu is one of Chris’ favorite dishes from Plenty by Ottolenghi. The book says it’s Chinese but it features Kecap Manis a Indonesian caramel sweet soy sauce which to my knowledge is never used in traditional Chinese cooking.  In short, deep fried tofu is drench in a sauce of kecap manis, Chinese light and dark soy sauces with plenty of sauteed shallots, ginger, garlic, red chillies and black pepper.

This recipe is almost perfect as a make-ahead dinner party dish because the flavors of the aromatics and the sauce mingle and develop when kept overnight in a refrigerator. The problem is that the deep fried tofu can’t hold its crispiness in the sauce for more than 10 minutes. I’m not expecting the crunch to hold up in the sauce overnight but if the tofu can remain crispy for an hour or two, then the sauce can be cooked the night before and the tofu fried just before the party.

A quick google search turned up this excellent post How To Cook Crispy Tofu Worth Eating from seriouseats.com. Tips from the post:

1) Start with non-siken firm tofu – I’m already doing that.

2) Dry the tofu before frying – The post recommends slicing the tofu then pour hot salted water over the slices and dry between pieces of paper towels. Previously, I just slice the tofu, dry with paper towels once and deep fry them immediately after dusting with corn flour. I followed the blog advice this time –  blanched the tofu and dry. I had to change the paper towels (double layered) 3 times before they were satisfactorily dry (paper towel remains dry for 1 minute).

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3) Coat with a batter of corn flour and vodka – The seriouseats.com post conducted a series of experiments with Korean Fried Chicken and concluded that coasting tofu with a batter of cornstarch and vodka results in a superior crust compared to a mere dusting or corn flour (or rice flour, potato flour and combination). The finding that cornstarch is the best starch for crispy deep fried food is confirmed by a issue of Cook’s Illustrated so I did not attempt to reconfirm this result. Instead, the focal point of my test was to find out if a corn starch-vodka batter is indeed superior to a water-corn starch batter and a seltzer-corn starch batter.

Method

I split the 1 block of tofu into 4 sets:

  • Dry corn starch dusting (Control)
  • Batter of water and corn starch (1 tbsp liquid + 1 tbsp corn starch)
  • Batter of seltzer water and corn starch (1 tbsp liquid + 1 tbsp corn starch)
  • Batter of vodka and corn starch ( 1 tbsp liquid + 1 tbsp corn starch)

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I heated the peanut oil to 350 °F (tested with a instant read thermometer), and lowered each batch of tofu into the oil for 4 minutes, flipping once at 2 minutes. The temperature of the oil was tested and adjusted between the batches.

Yep, there was less tofu in the Control batch because I took some out to boil for Miss Clarey. On hindsight I should take taken a cube from each batch so that the amount of tofu deep fried each time would remain constant.

The tofu were then mixed with the sauce in 4 separate dishes.

Result

IMG_20140224_191407098

I wanted to test if the tofu would remain crisp after 1 hour but it was 8 pm by the time I was done so we just gave it a 10 minutes rest.

It was obvious that all 3 of the battered tofu were crispy and crunchier than the Control batch (dry dusting). Even though I dried the tofu more thoroughly then usual, there didn’t seem to be any improvement compared to my previous attempt. In fact all the tofu coated in batter (liquid + corn starch) did better, which caused me to revisit the wisdom of drying the tofu thoroughly. The blog post I referred to didn’t explain the rationale and from various other recipes, it seems like the drying of tofu is mainly to allow the tofu to absorb more marinate. Since there is no marinate in this recipe, maybe drying the tofu and then just applying a dry dusting of cornstarch was actually counter productive since it seems that liquid+cornstarch resulted in better texture.

Among the 3 test batches, the vodka-cornstarch batter coating resulted in the crispiest crust which remain crispy at the end of dinner (about 30 minutes after mixing with the sauce). The other two were less crispy and got progressively so with time.

Conclusion

So it’s definitely a vodka-corn starch batter for deep frying tofu next time and even if I’m out of vodka, water and cornstarch is better than just a dusting of corn starch.

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